WO2008022613A2

WO2008022613A2 - Method for generating a communication session control message using sip

Info

Publication number: WO2008022613A2
Application number: PCT/DE2007/001318
Authority: WO
Inventors: Frank Kowalewski; Holger Schmidt
Original assignee: Infineon Technologies Ag
Priority date: 2006-08-11
Filing date: 2007-07-25
Publication date: 2008-02-28
Also published as: WO2008022613A3; DE102006037749A1

Abstract

The invention relates to a method for generating a communication session control message for use in an IMS or Push-to-Talk system, a call control protocol message being generated according to the SIP protocol. For a communication session with a plurality of communication terminals, the call control protocol message contains address information indicating at least one communication terminal to which the call control protocol message is to be applied. Said address information is provided in a section of the call control protocol message outside an address field in which an address of a communication terminal can be indicated.

Description

1

METHOD FOR GENERATING A COMMUNICATION SESSION TAX RECORD USING SIP

The invention relates to a method for generating a communication session control message, a method for controlling a communication session with a plurality of communication terminals, a communication session control message generation unit, a communication terminal

15 and a communication session control unit.

, The 3rd Generation Partnership Project (3GPP) has developed a standard for the Internet Protocol Multimedia Core Network Subsystem (IMS) architecture.

20

In various communication services based on the IMS standard developed by the 3GPP, the Session Initiation Protocol (SIP) is used to establish a communication connection between two or more

25 communication terminals, for example, to set up a conference between two or more communication terminals.

It is desirable to have communication terminals and thus subscribers in an efficient manner

30 communication session, such as a conference to remove.

According to one embodiment of the invention, a method for generating a communication session control message is provided in which a call control protocol message is generated in accordance with the SIP protocol, wherein the call control protocol message control information 2, which specifies, for a communication session with a plurality of communication terminals, at least one communication terminal to be removed from the communication session, the control information being provided in an area of the call control protocol message outside an addressing range in which an address of a communication terminal to be removed is specified.

10 embodiments of the invention are illustrated in the figures and are explained in more detail below.

Show it

FIG. 1 shows a communication system according to an exemplary embodiment of the invention;

2 shows a communication system according to a

Embodiment of the invention; 20

3 shows a message flow diagram according to a

Embodiment of the invention;

FIG. 4 shows a flowchart according to an embodiment 25 of the invention; and

Figure 5 is a flowchart according to an embodiment of the invention.

An IMS, that is a communication network according to the IMS standard developed by the 3GPP, makes it possible to provide various communication services based on the Internet Protocol (IP) to a mobile terminal.

Such communication services include Voice over Internet Protocol (VoIP), video telephony and conferencing, for example. 3 For example, telephone conferences or push-to-talk sessions (PTT).

According to IMS, data transmission is based on the

5 communication services on the Internet Protocol. This makes it possible to provide communications services via all packet-based communications systems, such as a wireless local area network (WLAN), GPRS (General Packet Radio Service) ^'and the UMTS (Universal Mobile 10 Telecommunications System).

In particular, an IMS enables a wide variety of communication services to be made available to a broad user base.

15

Both the (IMS) conference service and the PTT service, in addition to a procedure for floor control and the establishment of conference rules (Conference Policy Control Protocol) and procedures that are on the SIP (Session

Among other things, it will provide procedures for creating, managing, terminating, entering, and exiting multimedia conferencing.

25 Furthermore, the conference service provides methods

Notify conference participants of specific conference-related information and events.

As part of this conference service, media of various kinds can be exchanged between participants in a conference.

For example, audio conferencing, video conferencing, 35 instant messaging conferences, such as chat conferencing, and gaming (game) conferencing can be provided. According to one embodiment of the invention, there is provided a star-shaped conference architecture of a communication system in which all conference participants are coupled by means of signaling links with a conference control program which controls the conference and which is executed on a so-called (conference) focus. The focus thus represents a logical unit in the IMS.

A conference address, referred to herein as a Conference Uniform Resource Indicator (C-URI), is associated with a particular conference associated with, ie, controlled by, and executed by a particular focus.

15

The conference address represents the conference, and a user of the communication system may join the conference using the conference address, for example.

Among other things, the Focus has access to the Conference Policy, which manages a Conference Policy Server (CPS).

In addition to the implementation of the conference rules, the Focus has the task of providing the conference-specific distribution of the media content to the conference participants.

For generating a conference, in different embodiments of the invention, two SIP procedures are provided, that is, two SIP-based procedures.

According to a first method, the user wishing to create the conference sends a "SIP INVITE" message to the conference factory URI. 35 5

The Conference Factory URI is the address of a conferencing server, that is, a server that can create and manage conferences with the associated focus.

5 The successful establishment of a SIP session (hereinafter also referred to as SIP communication session) with the conference server results in the generation of a focus, a C-URI assigned to it and thus a conference.

10 According to a second method of generating a conference, a previously reserved C URI is used.

In this case, there is also a focus associated with a reserved C-URI. To create a conference, the user sends a "SIP INVITE" message directly to the focus using the C-URI as above, in this case.

Upon receipt of this message, a conference is created 20 if it does not yet exist. This reserves the resources required for a conference and then enables them.

If a user wishes to join an existing conference 25, the user or the terminal he uses also sends a "SIP INVITE" message to the C-URI. The focus associated with this C-URI adds the user to the existing and C-URI specified conference upon receipt of this message. 30

From the user's point of view, there is no difference between the method of creating a conference and the method of entering a conference.

For the Focus, one difference is that it activates a reserved conference or adds a user to an existing conference. It is possible that entire address ranges may be reserved for conferences, such as a complete domain (e.g., conf.vodafone.com) or subdomains 5 (e.g., the address range of conferencel@conf.vodafone.com to conference9999@conf.vodafone.com).

These reserved address ranges can be used for conferences 10.

Ending a conference by a user would mean removing all participants from the conference. This is often synonymous with the resolution 15 of the signaling connection (SIP session) between the conference participants and the Focus.

According to SIP, a conference is not ended until all participants have left the conference. This is for example disadvantageous if a user has a

Has created the conference and is unable to ensure that when it leaves the conference, the conference is actually terminated.

25 In a conventional method for terminating the

Participation of a user in a conference by means of SIP messages, the SIP dialogue and thus the SIP session (also referred to as SIP communication session) between the conference participant and the Focus by means of a "SIP-BYE"

30 message finished.

In this way, as mentioned above, so far only the termination of the conference participation of a single conference participant is possible, but the conference is usually further away, if there are other participants in the conference. 7

It may i.a. an appropriate Conference Policy will be provided stating that the entire conference will be terminated as soon as a particular participant leaves the conference, but it is not a SIP-based method of terminating a conference that is SIP compliant and compatible with the current SIP standard known.

The removal of other participants or their communication terminals from a communication session,

10, for example, from a conference, is implemented using SIP, for example, with a REFER message. The REFER message contains on the one hand the information that the other participant has to be removed from the session (method = BYE) and, on the other hand, the SIP address of the one to be removed

15 participants.

As a SIP address of subscribers to be removed, a specific SIP address can be specified in an address range of the REFER message, or an address of the form

20 "* @ hostPart" (in other words, partial address information that is common to several communication terminals ("hostPart")). "* @ HostPart" means that all participants should be removed, the "hostPart" in the Host Part of their SIP The SIP specification allows

However, not the use of the universal selector "*" in the "hostPart" of the SIP address, for example, to select all communication terminals and possibly remove from the conference.

Furthermore, it should be noted that usually at a communication session participants with

Participate communication terminals with addresses with different host parts.

In general, a conference will therefore only be terminated if, as mentioned above, all participants in the conference have left the conference. This is particularly disadvantageous not only for tariff reasons, as described above, if a user pays the conference, but also in view of the 5 completeness of the SIP procedures and the SIP functionality within the conference service of the IMS.

According to the so-called "Caller Preferences for Session Initiation Protocol (SIP)", a user or user agent client (UAC) used by the ten user can specify preferences for how his request should be handled.

Here, two types of preferences can be distinguished. 15

Preferences of the first type are called "request handling preferences" and give the server special instructions on how to handle the request.

These instructions indicate, for example, that the request should be routed simultaneously to different contact addresses and thus communication terminals of a user called by the user, which is referred to as "forking", or that the different ones

25 contact addresses should be contacted successively, which is referred to as "search sequentially".

In this case, the instructions are transmitted in the message header field (header) with the designation "request-disposition" of a SIP 30 request (SIP request).

Preferences of the second type are referred to as "feature preferences" and allow the user sending a SIP request to specify a set of features that describes what properties the called user's UA (User Agent) should have. 9

A SIP capable communication terminal that sends SIP requests (SIP requests) and responds to requests with SIP responses (SIP responses) is called SIP UA (User Agent). Thus, a UA has a user agent client (UAC) 5 that can send requests, and a UAS (User Agent Server) that can respond to requests.

In one or more embodiments of the invention, it is assumed that each communication terminal includes a 10 UA.

To transfer feature preferences, the message header field named Accept-Contact and the message header field named Rejsct-Contact 15 are used.

The specification of the properties or the feature preferences is carried out by means of so-called "feature tags", that is to say by means of specific identifiers (tags) in the mentioned 20 message header digits, for example by means of so-called base tags (base tags), which are part of SIP to be provided.

However, it is allowed within the IETF standard to define another 25 tags.

During the establishment of a session, the properties required of a calling user are compared with the characteristics of the UA associated with each contact address of the called user.

Subsequently, the UA (and the corresponding contact address) whose properties best correspond to the properties required by the calling user is selected. 10

The request of the calling user is forwarded to this contact address.

For example, this method is used to indicate that a UA is a focus. For this purpose, the UA inserts the SIP feature tag named "isfocus", which is a base tag, as a parameter into the Contact Header message header field of a SIP message transmitted to another UA. The other UA receiving the SIP 10 message with the corresponding "Contact Header" recognizes that the UA that sent the SIP message is a Focus and has corresponding functions.

In a so-called SIP REFER method, a conference participant may request a focus, a SIP message specified within a REFER message, for example a BYE message or an INVITE message, as described below, to one in the REFER message specified address, eg in the form of a SIP 20 URI.

By means of the SIP-REFER message, the focus can be requested by a conference participant, for example, to send a SIP INVITE message to a specific Nμtzer or its UA 25. This user is thus invited to join the conference.

The user is thus invited by the conference participant who sent the REFER message to the focus.

30

By means of the SIP-REFER message, the focus may also be requested by a conference participant, for example, to send a SIP-BYE message to a specific user or his UA. This user will look like this

35 of the conference away. 11

In this case, the user is causally removed by the conference participant who sent the REFER message to the focus.

5 shows a communication system 100 according to an embodiment of the invention.

The communication system 100 is implemented according to the UMTS architecture described by 3GPP, whose integral

10 part of the IMS is. It should be noted that in an alternative embodiment of the invention, the communication system 100 also according to another architecture, such as another mobile radio architecture or a fixed network architecture,

15 may be established.

A communication terminal 101 is coupled to an IMS 111 via an access network 102. In one embodiment of the invention, any number 20 ^' of communication terminals are included in the communication system 100 and can communicate with each other via the communication system 100.

The access network 102 may include, for example

25 mobile communication network according to the UMTS standard, i. a Universal Terrestrial Access Network, which allows access of the communication terminal to the IMS 111 by means of a packet-switched domain, or an access network according to the GSM standard, i. a GSM EDGE Radio Access Network.

30

The access network 102 may also be a landline network, for example, the communication terminal 101 may include a device that allows access to the Internet, for example a DSL (Digital Subscriber Line),

35- modem. In this example, the communication terminal is coupled to the IMS 111 via the Internet. 12

According to the embodiment of the access network 102, the communication terminal 101 is, for example, a mobile telephone or a computer with or without a mobile radio module.

In this embodiment, the access network 102 is a mobile radio communication system according to the UMTS communication standard.

A mobile radio network 112 of the access network 102 has the architecture of a UMTS radio network, which is also known as UMTS radio network.

Terrestrial Radio Access Network (UTRAN) is referred to.

The access network 102 has a PS domain 140, which consists of the

There are 15 components SGSN (Serving GPRS Support Node), GGSN (Gateway GPRS Support Node) and the interface for packet-switched connections between the mobile network 112 and. external packet-based data networks, such as the Internet, forms and access to the IMS 111 realized.

20

Accordingly, the PS domain 140 performs all functions to ensure the transport of packet-switched data. Furthermore, it enables the transport of signaling messages to the IMS.

25

The access network further comprises an HLR 141, which is a central database in which all information is stored by subscribers required, inter alia, to establish a connection and to manage services

30 are.

By means of the access network 102, the communication terminal 102 is coupled to a P-CSCF (CSCF: Call Session Control Function, P-CSCF: Proxy-CSCF) 103 of the IMS 111. 35 13

The P-CSCF 103 serves as an exchange and is coupled to a DNS (Domain Name Server) 104 and an I-CSCF (Interrogating CSCF) 105.

5 The I-CSCF 105 is coupled to an HSS 106 (Home Subscriber Server) 106 and an S-CSCF (Serving CSCF) 107.

The S-CSCF 107 is coupled to a plurality of application servers (AS, Application Server), of which only one application server 138 is shown.

The S-CSCF 107 is further coupled to an MRFC (Media Resource Function Controller) 142.

By means of the application server 138 and the MRFC 142, a conference server and at least one focus are realized.

The communication terminal 101, the access network 102, the P-CSCF 103 and the DNS 104 are parts of the visited network 20 (V-PLMN) 109.

The I-CSCF 105, the HSS 106, the S-CSCF 107 and the application server AS 138 and optionally the MRFC 142 are part of the Home Communications Network (H-PLMN) 108.

25

In one embodiment of the invention, the P-CSCF 103, the I-CSCF 105, the HSS 106, and the S-CSCF 107 are part of the IMS (IP Multimedia Core Network Subsystem) 111. In another embodiment of the invention, it is contemplated .

30 that the P-CSCF 103, the I-CSCF 105, the HSS 106 and the S-CSCF 107 are located outside of the IP Multimedia Core Network Subsystem 111.

By means of the communication terminal 101, a user can use the 35 communication services of the IMS 111, for example an "instant message" to another communication terminal coupled to the communication system 100 14 or perform a conference with users of other communication terminals coupled to the communication system 100.

5 shows a communication system 200 according to another embodiment of the invention.

The communication system 200 according to the exemplary embodiment illustrated in FIG. 2 is configured according to the push-to-talk over cellular

10 system set up according to the standard of the Open Mobile Alliance (OMA). In this embodiment, the participants or the communication terminals of the participants in a conference do not communicate directly with each other, but via a central PTT server.

15

In one embodiment of the invention, a PTT server 201 and four communication terminals 202, 203, 204, 205 (also referred to as subscriber terminals), namely a first communication terminal 202, a second

20 communication terminal 203, a third

Communication terminal 204 and a fourth communication terminal 205, which participate in a PTT session (hereinafter also referred to as conference). The participants or the communication terminals

25 202, 203, 204, 205 communicate by audio. In an alternative embodiment of the invention, the communication terminals 202, 203, 204, 205 communicate alternatively or additionally by video.

30 The connection control between the

Communication terminals 202, 203, 204, 205 and the central PTT server 201 via SIP.

A first participant Tl and thus the first

35 communication terminal 202 generates the PTT session by the other participants (for example, second party T2, third party T3 and fourth party T4) and their 15

Communication terminals (for example, second communication terminal 203, third communication terminal 204 and fourth communication terminal 205) to the PTT session invites. The first participant T1 is thus automatically authorized to remove the other participants from the PTT session.

After the first participant Tl has clarified all questions with the other participants T2 to T4, with these

10 participants want to be clarified, the first would like

Participants Tl discuss the results further with other participants. For this Tl selects at his communication terminal the option of all subscribers (except Tl), i. in this' embodiment of the invention, the second subscriber T2,

15 the third party T3 and the fourth party T4 to remove from the PTT session.

In order to remove the other participants from the PTT session, the first communication terminal 202 of the first 20 subscriber Tl sends a SIP REFER message to the PTT server 201.

In one exemplary embodiment of the invention, the SIP REFER message contains the SIP address of one of the subscribers of the PTT session (here, for example, the SIP address of the second subscriber T2) as a refer-to address. The Refer-To-Header field also specifies the generic parameters "method = Bye" and "Refer-To-Extension = * &! Tl ^Nλ .

The following Table 1 shows the details of the REFER message according to an embodiment of the invention: 16

REFER sip: ptt@atlanta.example.com SIP / 2. O

Via: SIP / 2. O / ÖDP agent. Atlanta. example. com; branch = z9hG4bK2293940223

To: <sip: ptt @ atlanta. example. com>

From: <sip: Tl>; tag = 193402342

Call ID: 898234234@agenta.atlanta.example.com

CSeq: 93809823 REFER

Max forwards: 70

Refer-To: <sip: T2; method = BYE; Refer-To-Extension = * &! Tl>

Contact: sip: Tl

Content-Length: 0

Table 1 :

REFER message for removing all participants from the PTT-5 session except for the first participant T1;

In the message shown in Table 1, the terms "Tl" and "T2 ^λλ for the SIP addresses are from the

Communication terminals 202, 203 of the first subscriber Tl 10 and the second subscriber T2.

The address of the second subscriber T2 is indicated in an address area of the message shown (see in the message "Refer-To: <sip: T2; ...>"). With this address

15, it is indicated that the PTT server 201 (at a

Embodiment according to a structure according to Fig.l the focus) should send a SIP BYE message (indicated by the parameter "method = BYE") to the communication terminal 203 of the second subscriber T2 and thus the

20 communication terminal 203 of the second subscriber T2 to remove from the PTT session.

The generic parameter "method = Bye ^λλ thus means that the PTT server 201 the second subscriber T2 or its

25 communication terminal 203 (generally to the subscriber or its communication terminal, which is specified in the address range of the refer-to field) should send a SIP BYE message. As a result, the connection between the PTT server 201 and the second subscriber T2 or its

30 communication terminal 203 completed. 17

The additional generic parameter "Refer-To-Extension = * &! T1" (according to the message shown in Table 1, located outside the address range of the refer-to field) signals to the PTT server 201 that it also allows all 5 other participants ( For example, thus the third subscriber T3 and the fourth subscriber T4) or their communication terminals (for example, the third communication terminal 204 and the fourth

Communication terminal 205) of the PTT session except the first 10 participants Tl or its communication terminal 202 a

SIP-BYE message should send. As a result, these subscribers or these communication terminals are also removed from the PTT session.

Thus, according to one embodiment of the invention, it is generally provided to use SIP messages with special information to identify all participants in a communication session by one of the participants from the session (e.g., a PTT session, generally one

20 any SIP-controlled session) except for one or more designated subscribers. The special information indicates that all participants should be removed from the session except for one or more dedicated subscribers.

25

For example, to remove all subscribers from a communication session, a subscriber may send a SIP REFER message to the central server (eg, PTT server 201, as an alternative to the focus of a conference in a

30 communication system 100 according to Fig.l) of the communication system 100, 200 send.

The REFER message, according to one embodiment of the invention, has the structure of a normal REFER message for removing a single other subscriber (addressed in an address range of the REFER message) from the session with an additional special parameter (included outside 18 of the address range) signaling the desire to remove all participants from the session to one or more dedicated subscribers. The additional parameter can be eg: "Refer-To-Extension = * &! Tl "or 5" Expel-AU-But-Me ".

The additional parameter can be specified, for example, as an additional generic parameter in the refer-to-header field or as text in the body of the REFER message.

10

Another way to remove all participants from a communication session with a REFER message is to use a REFER message with "method = Bye" and a special refer-to address

15 Refer-To Address represents all participants in the session except for one or more designated participants. In other words, the refer-to address refers to a specific instruction, with the removal of all participants except for the first participant

20 Tl is instructed from the conference. For example, if the session is identified by the session identifier "SessionID", the REFER message could use the refer-to address "ParticipantsExceptTl.SessionID" to indicate that in the conference (otherwise

25, session) identified by the session identification information "SessionID", all the participants except for the first party Tl are to be removed.

In another embodiment of the invention, it is provided that a predeterminable number of subscribers are to be removed from the communication session, wherein an arbitrarily predeterminable number of subscribers or their communication terminals are excluded from the removal

35 should remain. In this way, with an additional option, a very efficient control and management of a communication session is achieved. For example, can 19 be provided that all participants are to be removed from the communication session except for exactly one, which is uniquely addressed, for example, the subscriber or its communication terminal, which has generated the 5 communication session.

Another way to remove all participants by SIP message from a session is in an alternative embodiment of the invention therein, instead

10 of a REFER message using a SIP MESSAGE message. The MESSAGE message may be in its body e.g. the text "Refer-To: * &! Tl; method = Bye "to signal the removal of all participants (except Tl) from the session, in which case the expression" * &! T1 "

15 referred to the number of participants that includes all participants of the communication session (all participants are referenced with the symbol "*") except for (the symbol "&!" Stands for the logic function "AND NOT") the first participant (called with "Tl").

20

An advantage of an embodiment of the invention can be seen in the fact that the participants of a communication session with a single SIP message can be removed from the session. This is the

25 signaling such a statement very efficient and easy.

Further, the SIP messages used conform to the SIP specification because they do not use a universal selector "* ^λλ in the host 30 part of the refer-to address.

When REFER messages are used to remove the subscribers, the message type also corresponds to the previously commonly used SIP message to send individual subscribers of a communication session from the

Remove communication session. The proposed solution according to these embodiments of the invention is therefore 20 consistent with the previous solution for removing individual participants.

An embodiment of the invention also has the advantage that the solution can be used with devices that do not understand the proposed special signaling. According to the conventional SIP specification, such devices simply ignore the signaling.

In an exemplary embodiment of the invention, it is achieved in a multi-subscriber communication system to allow the subscribers of a communication session to remove all subscribers from the communication session.

FIG. 3 shows a message flow diagram 300 according to an embodiment of the invention.

The message flow shown in Figure 3 takes place between a first communication terminal 301, a P-CSCF 302, 20 which is part of a visited network 303, an S-CSCF 304 and an application server 306, which is part of the ^'home network 305 are of the communication terminal, and a second communication terminal 322 instead.

The application server 306 in this embodiment is a conference server.

In the embodiment described below, the SIP-REFER method is used to terminate a conference. 30

In 307, the user of the communication terminal 301 sends a SIP "REFER" message containing a C-URI to the P-CSCF 302 via the communication terminal 301.

For example, the REFER message is constructed in the same or similar manner as the REFER message shown in Table 1, as described above. 21

For example, the REFER message has a header field labeled "Refer-To", and this header field contains the C-URI and the value 5 "BYE" of a parameter named "method", that is, the header field contains the string " method = BYE ".

In 308, the P-CSCF 302 forwards the REFER message to the S-10 CSCF 304. _,

In 309, the S-CSCF 304 forwards the REFER message to the application server 306, which provides the focus 321.

At 310, Focus 321 checks to see if the referral

Message header field in the REFER message containing C-URI and the string "method = BYE".

If the refer-to header field in the REFER message contains the C-URI and the string "method = BYE", the focus 321 terminates the communication session corresponding to the C-URI for all subscribers of the communication session except for the first subscriber Tl or Tl. its communication terminal 202, as in the Refer-to-25 message header field in the REFER message the

Additional information "Refer-To-Extension = * &! Tl" is included.

In 311, the focus 321 transmits to the communication terminal 301 an acknowledgment for the receipt of the REFER message 30 by means of a "202 Accepted" SIP message, which is transmitted to the S-CSCF 304.

In 312, the S-CSCF 304 forwards the accepted message to the P-CSCF 302, which transmits the accepted message in 313 to the communication terminal 301. 22

Since in this example the additional information "Refer-To-Extension = * &! Tl" and the string "method = BYE" are contained in the REFER message, in 314 the focus 321 ends the communication session for all participants 5 except for the first one Participants Tl, by the SIP dialogues to all conference participants or their,

Terminates communication terminals (for example, to the second communication terminal 322) and releases the resources used for the conference.

10

^• For example, the participation of the user of the second communication terminal 322 which corresponds, for example according to the second communication terminal 203 in the communication system 200 Fig.2 is used, terminated. Therefore transmits

15 in 315, the focus 321 sends a message labeled "BYE" to the S-CSCF 304 for forwarding to the second communication terminal 322.

In 316, the S-CSCF 304 forwards the BYE message to the P-CSCF 20 302, which transmits the BYE message to the second communication terminal 322 in step 317.

In 318, the second communication terminal 322 acknowledges receipt of the BYE message by transmitting a message labeled "200 OK" to the P-CSCF 302 for forwarding to the application server 306.

In 319, the P-CSCF 302 forwards the OK message to the S-CSCF 304, which transmits the OK message in 320 to the Focus 321 30.

Thus, for example, after receiving the REFER message, the focus 321 transmits to all communication session participants except the first user Tl a BYE message, since the communication terminals of all

Communication session participants except for the first participant Tl by means of the additional information "Refer-To- 23

Extension = * &! Tl "are specified as communication terminals to be removed from the communication session.

By transmitting a BYE message to all participants 5 except for the first party Tl and then stopping the

Communication session by the first participant Tl the communication session can be terminated easily and cost-effectively targeted.

10 It should be noted that in an alternative

Embodiment of the invention, the removal of the participants or their communication terminals the

Communication session does not necessarily end. In one embodiment of the invention, it is also envisaged that

15 the communication session persists, but temporarily without participants. At a later time, participants can again join the communication session and the communication can be continued in the same communication session with the same session ID. In this

Nevertheless, a very efficient removal of the participants from the communication session is achieved.

Targeted removal of the subscribers may be achieved as described using only a single REFER message sent by the user, using a very simple additional command in a SIP message.

In this way, an implicit termination of the conference is achieved by means of SIP messages.

30

According to various embodiments of the invention, the at least one conference provided by the conference server (as an example of a communication session) is a multimedia conference, for example an audio conference,

35 a video conference, an instant messaging conference, such as a chat conference, or a gaming (game) conference. 24

4 shows in a flowchart 400 a method for controlling a communication session with a plurality of communication terminals according to an embodiment of the invention. 5

In 402, control information is determined from a received call control protocol message according to the SIP protocol, with which for a communication session with a. Plurality of communication terminals at least one

10 communication terminal is specified, which from the

Communication session is to be removed, wherein the control information is provided in an area of the call control protocol message outside an addressing area in which an address of an

15 removing communication terminal is specified.

In 404, according to the determined control information, the at least one communication terminal is removed from the communication session. 20

In the following some alternative embodiments of the invention will be explained in more detail.

Instead of sending the generic parameter "Refer-To-Extension = * &! Tl" 25 in the REFER message of the above example (Table 1), the parameter "Expel-All-But-Me ^Xλ " can also be used and sent. Table 2 below shows the corresponding REFER message.

REFER sip: ptt8atlanta.example.com SIP / 2.0

Via: SIP / 2.0 / üDP agenta. Atlanta. example. com; branch = z9hG4bK2293940223

To: <sip: pttδatlanta. example. com>

From: <sip: Tl>; tag = 193402342

Call ID: 898234234 @ agenta. atlanta. example. com

CSeq: 93809823 REFER

Max forwards: 70

Refer-To: <sip: T2; method = BYE; Expel-All-But-Me>

Contact: sip: Tl

Content-Length: 0

30

Table 2: 25

Alternative REFER message to remove all participants from the communication session to the first

Participants Tl

5 The terms "Tl" and "T2" in the message shown stand for the SIP addresses of the communication terminal of the first subscriber Tl and the second subscriber T2.

Instead of sending "Refer-To-Extension = * &! Tl" or "Expel-All-But-Me" 10 as a generic parameter in the refer-to-header field, you can also use these text lines in the body of the Send REFER message. The following table 3 shows the corresponding REFER message.

REFER sip: ptt@atlanta.example. com SIP / 2.0

Via: SIP / 2.0 / UDP agent. Atlanta. example. com; branch = z9hG4bK2293940223

To: <sip: ptt@atlan.ta. example. com>

From: <sip: Tl>; tag = 193402342

Call ID: 898234234@agenta.atlanta.example.com

CSeq: 93809823 REFER

Max forwards: 70

Refer-To: <sip: T2; method = BYE>

Contact: sip: Tl

Content-Type: text / plain

Content-Length: 24

15 Refer-To-Extension = * &! tl

Table 3: Alternative REFER message for removing all participants from the communication session, except for the first 20 participants Tl

The terms "Tl ^λΛ and" T2 ^M in the message shown stand for the SIP addresses of the communication ^{terminal of} the first subscriber Tl and the second subscriber T2.

25

Rather than signaling the removal of all or all except certain participants by generic parameters or a special body text, the REFER message may also include a special refer-to address. The address

30 identifies the group of participants to be removed from the session. For example, the address may be from the 26

Session ID "SessionID" and an addition may be formed, for example: "ParticipantsExceptTl.SessionID". In this case, all participants except the first participant Tl are removed from the communication session. The following table 4 shows the corresponding REFER message.

REFER sip: ptt @ atlanta. example. com SIP / 2. 0

Via: SIP / 2. O / üDP agenta. atlanta. example. com; branch = z9hG4bK2293940223

Toe: <sip: ptt @ atlanta. example. com>

From: <sip: Tl>; tag = 193402342

Call ID: 898234234 @agenta. atlanta. example. com

CSeq: 93809823 REFER

Max forwards: 70

Refer-To: <sip: ParticipantsExceptTl. SessionID; method = BYE>

Contact: sip: Tl

Content-Length: 0

^'Table 4:

10 Alternative REFER message to remove all participants from the communication session, except for the first participant

tl

The term "Tl" in the message shown stands for the 15 SIP address of the communication terminal of the first

Subscriber Tl. The term "SessionID" stands for the SIP address of the communication session.

It is provided in an alternative embodiment of the invention 20 to address all subscribers without exception, for example by the address from the session ID "session ID" and an addition is formed, which invariably all participants of the communication session, for example: "Participants ". 25

Instead of signaling the removal of the subscribers with a SIP REFER message, the distance can also be signaled with a SIP MESSAGE message. The SIP MESSAGE message then contains the expression "Refer-To: * &! Tl; method = Bye ^{λλ in the body} . In this case, all participants except for the first participant Tl from the 27

Communication session removed. Table 5 below shows the corresponding MESSAGE message.

MESSAGB sip: ptt @ atlanta. example. com SIP / 2. 0

Via: SIP / 2. O / UDP agent. atlanta. example. com; branch = z9hG4bK2293940223

To: <sip: ptt @ atlanta. example. com>

From: <sip: Tl>; tag = 193402342

Call ID: 898234234 @agenta. atlanta. example. com

CSeg: 93809823 MESSAGE

Max forwards: 70

Contact: sip: Tl

Content-Type: text / plain

_{Content-Length:.} 25

Refer-To: * &! Tl; method = Bye

Table 5:

MESSAGE message for removing all participants from the communication session, except for the first participant Tl

10 The expression "Tl" in the message shown stands for the SIP address of the communication terminal of the first subscriber Tl.

It is provided in an alternative embodiment of the invention 15 to address all participants without exception, for example, by the MESSAGE message in the body area contains the expression "Refer-To: *; method = BYE".

Another possibility can be provided for removing all 20 subscribers including the requesting subscriber (in the above example the first subscriber T 1) from the communication session. The REFER message of the first example then contains "Refer-To-Extension = *" as the generic parameter instead of "Refer-To-Extension".

25 Extension = * &! Tl "(alternatively, for example, another specified expression such as" Expel-All-Including-Me "instead of" Expel-All-But-Me ".) Table 6 below shows the corresponding REFER message. 28

REFER sip: ptt @ atlanta. example.com SIP / 2.0

Via: SIP / 2.0 / UDP agent. atlanta.example. com; branch = z9hG4bK2293940223

To: <sip: pttΘatlanta. example. com>

From: <sip: Tl>; tag = 193402342

Call ID: 898234234@agenta.atlanta.example.com

CSeq: '93809823 REFER

Max forwards: 70

Refer-To: <sip: T2; method = BYE; Refer-To-Extension = *>

Contact: sip: Tl

Content-Length: 0

Table 6: -

REFER message to remove all ^Participant of the five communication session

The terms "Tl" and "T2" in the message shown stand for the SIP addresses of the communication terminal of the first subscriber Tl and the second subscriber T2.

10

It should be noted that the invention is not limited to a PTT system. As described above, it may also be used in other multi-party communication systems, for example in other conferencing systems, such as e.g. in

15 a conference system according to the IETF, are used.

FIG. 5 shows in a flow diagram 500 a method for. Controlling a communication session with a plurality of communication terminals according to an embodiment of the invention.

In 502, address information is determined from a received call control protocol message in accordance with the SIP protocol, with which for a communication session with a

25 plurality of communication terminals at least one

Communication terminal is specified, to which the call control protocol message is to be applied, wherein the address information is provided in an area of the call control protocol message outside of one

30 addressing area in which an address of a communication terminal is specified. 29

In 504, according to the determined address information, the call control protocol message is applied to the at least one communication terminal.

In one embodiment of the invention, there is provided a method of generating a communication session control message, comprising generating a call control protocol message in accordance with the SIP protocol, wherein the call control protocol message includes control information

10 is specified for a communication session with a plurality of communication terminals at least one communication terminal to be removed from the communication session, wherein the control information in a range of call control

15 protocol message is provided outside of an addressing area in which an address of a communication terminal to be removed can be specified.

A communication terminal to be removed can be specified in the 20 addressing range.

In one embodiment of the invention, the control information contains an instruction indicating that a predeterminable number of communication terminals should be removed from the communication session.

In one embodiment of the invention, the control information includes an instruction to indicate that all communication terminals should be removed from the communication session.

In one embodiment of the invention, the control information contains an instruction indicating that all the communication terminals are from the

35 communication session are to be removed except for one or more predetermined communication terminals. 30

Communication should be removed except for the 5 Cail Control Protocol message generating communication terminal.

The control information can be inserted in the form of a referencing in the call control protocol message. 10

Furthermore, the referencing can be inserted in the refer-to-message header field.

The at least one communication session provided by the conference server may be a multimedia communication session.

In one embodiment of the invention is a communication session control message generation unit

20, which is configured to generate a call control protocol message in accordance with the SIP protocol, wherein the call control protocol message contains control information with which at least one communication session with a plurality of communication terminals

25 communication terminal is specified, which from the

30 removing communication terminal is specified.

In one embodiment of the invention, the communication session control message generating unit is further configured such that one of the

35 communication session to be removed communication terminal is specified in the addressing area. 31

In one embodiment of the invention, the communication session control message generating unit is further configured such that the control information includes an instruction indicating that a predetermined number of communication terminals should be removed from the communication session.

In one embodiment of the invention, the communication session control message generating unit 10 is further configured such that the control information includes an instruction indicating that all communication terminals should be removed from the communication session.

In one embodiment of the invention, the

Communication session control message generating unit further configured such that the control information includes an instruction that indicates that all communication terminals from the communication session

20 are to be removed except for one or more predetermined communication terminals.

In one embodiment of the invention, the communication session control message generating unit is

25 further configured such that the control information includes an instruction indicating that all communication terminals should be removed from the Kornmunikationsssitzung except for the call control protocol message generating communication terminal.

30

In one embodiment of the invention, a communication terminal of a communication system is provided. The communication terminal points to a conference control message generation unit for generating

35 a call control protocol message according to the SIP protocol, wherein the call control protocol message contains control information with the for a 32

Communication session is specified with a plurality of communication terminals at least one communication terminal to be removed from the communication session, wherein the 5 control information is provided in an area of the call control protocol message outside of an addressing range in which specifies an address of a communication terminal to be removed becomes.

In one embodiment of the invention, a communication session controller of a communication system is provided. The communication session control unit points to a determination device that is set up from a

15 received call control protocol message according to the SIP protocol control information to be determined, is specified with the for a communication session with a plurality of communication terminals at least one communication terminal that from the

20 communication session is to be removed, wherein the control information is provided in an area of the call control protocol message outside an address range in which an address of a communication terminal to be removed is specified, and a

25 control, which is established according to, the determined

Control information to remove the at least one communication terminal from the communication session.

In another embodiment of the invention, a method for controlling a communication session with a plurality of communication terminals is provided. The method comprises determining, from a received call control protocol message in accordance with the SIP protocol of control information, with which for a communication session with a plurality of communication terminals at least one communication terminal is specified, which is to be removed from the communication session, the 33

Control information is provided in an area of the call control protocol message outside of an addressing area in which an address of a communication terminal to be removed is indicated, and a removal according to the determined control information of the at least one communication terminal from the communication session.

In another embodiment of the invention, there is provided a method of generating a communication session control message comprising generating a call control protocol message in accordance with the SIP protocol, the call control protocol message including control information with which for a communication session with a plurality of communication terminals, indicating at least one communication terminal to be removed from the communication session, the control information being an address included in the call control protocol message and with an instruction is referenced to remove a predetermined number of communication terminals from the communication session.

25 The instruction may include an instruction to indicate that all communication terminals should be removed from the communication session.

The instruction may include an instruction to the 30 indicated ^1, is that all communication terminals from the

Communication session are to be removed except for one or more predetermined communication terminals.

The instruction may include an instruction to indicate that all communication terminals are from the

Communication session to be removed except for the 34

Call control protocol message generating communication terminal.

In another embodiment of the invention, a method for generating a communication session

A control message is provided, comprising generating a call control protocol message in accordance with the SIP protocol, wherein the call control protocol message contains control information with which for a communication session with a

10 plurality of communication terminals more

Communication terminal to be removed from the communication session, and with the at least one communication terminal is specified, which should not be removed from the communication session.

15

The control information may include an instruction to indicate that all communication terminals should be removed from the communication session except for the one generating the call control protocol message

20 communication terminal.

Claims

35 claims

A method for generating a communication session control message, comprising

5 • generating a call control protocol message according to the SIP protocol,

• wherein the call control protocol message contains address information with which for a communication session with a plurality of

10 communication terminals at least one

Communication terminal is specified, to which the call control protocol message is to be applied, wherein the address information is provided in an area of the call control protocol message

15 outside of an addressing area in which a

Address of a communication terminal can be specified.

2. Method according to claim 1,

20 wherein a communication terminal to be removed is specified in the addressing area.

3. The method of claim 1, wherein the address information indicates that the Call Control message should be applied to a predeterminable number of communication terminals from the communication session.

4. The method according to claim 3,

30 wherein the address information indicates that the Call Control Protocol message is at all

Communication terminals from the communication session to be applied.

5. The method of claim 3, wherein the address information indicates that the Call Control Protocol message applies to all 36

Communication terminals from the communication session to be applied to one or more predetermined communication terminals.

6. The method of claim 3, wherein the address information indicates that the Call Control Protocol message applies to all

Communication terminals from the communication session • should be applied except for the communication terminal generating the call control protocol message.

7. The method of claim 1, wherein the communication terminals are configured for communication according to a 3GPP standard. 15

8. The method according to claim 1, wherein 'the address information is inserted in the form of a referencing in the call control protocol message.

The method of claim 1, wherein the referencing is inserted in the refer-to header field.

10. The method according to claim 1,

25 wherein the at least one communication session provided by the conference server is a multimedia communication session.

11. Communication session control message generation unit, set up for

Generating a call control protocol message according to the SIP protocol,

• where the call control protocol message contains address information for a

35 communication session with a plurality of

Communication terminals at least one communication terminal is specified, to which the 37

Call control protocol message ^" is to be applied, wherein the address information is provided in an area of the call control protocol message outside of an addressing area in which a 5 address of a communication terminal is specified.

The communication session control message generation unit according to claim 11, further configured such

10 that a communication terminal to be removed from the communication session is specified in the addressing area.

The communication session control message generation unit 15 of claim 11, further configured such that the address information indicates that the Call Control Protocol message is to be applied to a predeterminable number of communication terminals from the communication session. 20

14. The communication session control message generation unit of claim 13, further configured such that the address information indicates that the Call Control Protocol message applies to all

25 communication terminals from the communication session to be applied.

The communication session control message generation unit according to claim 14, further configured such

30 that the address information indicates that the call

Control log message at all

Communication terminals from the communication session to be applied to one or more predetermined communication terminals. 35

16. The communication session control message generation unit according to claim 14, further configured such 38 that the address information indicates that the call control protocol message is at all

Communication terminals from the communication session to be applied except for the call control 5 protocol message generating communication terminal.

17. Communication terminal of a communication system, comprising the communication terminal:

A conference control message generation unit

10 for generating a call control protocol message according to the SIP protocol,

15 communication terminals at least one

20 outside of an addressing area in which a

Address of a communication terminal is specified.

18. Communication session control unit of a

25 communication system comprising the communication session control unit:

A determination device, which is set up, receives address information from a received call control protocol message in accordance with the SIP protocol

30 to determine with the for a

Communication session is specified with a plurality of communication terminals at least one communication terminal to which the call control protocol message are applied

35, wherein the address information is provided in an area of the call control protocol message outside an addressing area in which a 39

Address of a communication terminal is specified ■; and

A controller which is set up according to the determined address information the call control

5 protocol message to the at least one addressed communication terminal to apply.

19. A method for controlling a communication session with a plurality of communication terminals, the method

10 comprising:

Determining from a received call control protocol message according to the SIP protocol of address information; with the for a communication session with a plurality of

15 communication terminals at least one

20 outside of an addressing area in which a

Address of a communication terminal is specified; and

Apply, according to the determined address information, the call control protocol message to the

25 at least one communication terminal.

20. A method for generating a communication session control message, comprising

Generating a call control protocol message 30 according to the SIP protocol,

Wherein the call control protocol 1 message contains address information for at least one communication session with a plurality of communication terminals

35 communication terminal is specified, to which the

Call control protocol message to be applied .soll, where the address information is an address, 40 contained in the call control protocol message and referring to a set of subscribers.

21. The method of claim 20, wherein the set of participants all

Communication terminals from the communication session are.

22. Method according to claim 20, wherein the quantity of participants is all

Communication terminals from the communication session are predefinable except for one or more

Communication terminals. 15

23. The method according to claim 20, wherein the amount of participants all

Communication terminals from the communication session are up to the call control protocol message 20 generating communication terminal.

24. A method for generating a communication session control message, comprising

Generating a call control protocol message 25 according to the SIP protocol,

Wherein the call control protocol message contains address information with which a plurality of communication terminals are used for a communication session with a plurality of communication terminals

30 communication terminal are specified, to which the call control protocol message is to be applied, and with the at least one communication terminal is specified to which the call control protocol message is not applied

35 should be.

25. The method according to claim 24, 41

where the address information indicates that the Call Control Protocol policy is on all

Eosrouπikationsendgeräte from the Korπmunikationsssitzung applied / erάen is up to the Call Control Pxotokoll message generating Koπsnunikationsβπdgerät.