WO2003065665A1

WO2003065665A1 - Gateway and calling device

Info

Publication number: WO2003065665A1
Application number: PCT/SE2002/000135
Authority: WO
Inventors: Rasmus Bengtsson
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2002-01-28
Filing date: 2002-01-28
Publication date: 2003-08-07

Abstract

The present invention relates to a calling device (12) for packet switched telephony. According to the invention the calling device (12) is arranged to send a call address to an address selector (16) in a residential gateway (11), said residential gateway (11) being arranged to work as an interface between a circuit switched network and a packet switched network. The present invention further relates to a residential gateway (11) for telephony, arranged to work as an interface between a circuit switched network and a packet switched network. According to the invention the residential gateway (11) includes an address selector (16) arranged to select between receiving a call address from a terminal (10) in the circuit switched network or from a calling device (12).

Description

GATEWAY AND CALLING DEVICE TECHNICAL FIELD

The present invention relates to a gateway and a calling device for use with packet switched networks.

BACKGROUND OF THE INVENTION

IP telephony or Voice over IP (Internet Protocol) is a way of using a packet switched net, such as LANs and the Internet, for telephony, instead of the traditional circuit switched net that also is called PSTN (Public Switched Telephone Network) . There exist also other packet switched solutions, such as Voice over ATM (Asynchronous Transfer Mode) , Voice over FR (Frame Relay) , and also combinations of solutions such as Voice over IP over ATM, Voice over IP over FR and Voice over IP over Ethernet, see e.g. EP0841831 and W099/29135. The technology for the future seems to be Voice over IP technology because IP packets can run independently of the type of transport network.

There are several standards for Voice over IP and these are for example H.323 with associated protocols by ITU-T (International Telecommunications Union - Telecommunications sector) and SIP (Session Initiation Protocol) described in RFC2543 by IETF (Internet Engineering Task Force) .

SUMMARY OF THE INVENTION

It will take a while before everyone has changed to the new voice over IP technology and bought special and expensive voice over IP telephones. This is solved today by placing a gateway between an old-fashioned telephone or other terminal and the packet switched network. The problem is then that said telephone only can use telephone numbers as calling address, which is rather difficult to remember. The purpose with the present invention is to provide a cheap and easy solution of providing a more flexible way of call addressing without forcing people to buy a new and expensive voice over IP telephone.

This is solved by using a calling device where a call address e.g. in the form of an e-mail address can be written and sent to the gateway. Further, the gateway includes an address selector and can choose between receiving a call address either from the telephone (in the form of a telephone number) or from calling device.

The advantages are that this is a cheap, simple, flexible and customer friendly solution that will enable the market for packet switched telephony to grow faster.

The invention will now be described in more detail with the help of preferred embodiments and enclosed drawings.

DESCRIPTION OF THE FIGURES

Figure 1 shows a block view of a packet switched telephone network.

Figure 2 shows an embodiment of the invention.

Figure 3 shows a simplified time diagram of the set up of a call in H.323 using a telephone.

Figure 4 shows a simplified time diagram of the set up of a call in H.323 using a calling device.

PREFERRED EMBODIMENTS

Today a standard telephone is still an analogue telephone, suitable for the analogue Public Switched Telephone Network

(PSTN) or other circuit switched network. There are also possibilities to place phone calls using a packet switched network, such as Internet, by using computers connected to said network. However, the sound quality using a computer as a telephone is not very good and it is not a very practical solution either, e.g. you would not really carry the computer around so that can talk and cook dinner at the same time. In the future it might be so that everyone have special telephones for a packet switched network, such as IP telephones, but until then there is a need for a solution where it is possible to use an old-fashioned analogue telephone. The same goes for other terminals than telephones .

In Fig 1 is shown a known solution. A first analogue telephone 1 is connected to a first gateway 2, which in its turn is connected to a packet switched network 3, such as Internet. A second analogue telephone 5 may then be connected via a second gateway 4 in a similar way and further a terminal in the form of a computer or a specially designed telephone 6 may be connected directly without any need for any gateway.

The gateway 2, 4 works as an interface between different networks, in this example a circuit switched network such as PSTN, which the analogue telephone 1, 5 employs, and the packet switched network. The gateway 2, 4 provides data format translation, control-signalling translation, audio codec translation, and also call setup and termination functionality on both sides of the packet switched network. The gateway 2, 4 may e.g. be situated locally near the analogue telephone 1, 5 as a residential gateway 2, in a switchboard or somewhere in the PSTN 8 as a network gateway 4. In the last alternative the caller thus calls the gateway 4, logs in and then has the possibility to from there call whomever he likes.

There is normally also some kind of mapping mechanism in the network which translates for example telephone numbers into IP-addresses or similar. In H.323 this is referred to as a gatekeeper 7 in the network 3. The gatekeeper may provide central management and control services. All endpoints, e.g. terminals and gateways, must be registered with the gatekeeper 7. The registration phase informs the gatekeeper 7 which terminals and gateways are active and which addresses they are reachable on. In H.323 the gatekeeper 7 and the endpoints it administers form a management zone. A gatekeeper provides several services to all endpoints in its zone. The gatekeeper 7 maintains a database for translation between address aliases, such as telephone numbers and network addresses.

Further, but not important for the present invention, the gatekeeper 7 provides admission and access control of endpoints based on e.g. bandwidth availability, limitations on the number of simultaneous calls or the registration privileges of endpoints. The gatekeeper 7 also provides bandwidth management and has also the possibility to route all calls originating or terminating in its zone.

Other names for gatekeeper 7 are IP-PBX, soft-PBX, SIP proxy etc, depending on the standard used. Irrespective of the name, the common function is the ability to translate and inform terminals and gateways of reachable addresses to each other. In this description the word "gatekeeper", as is used in the standard H.323, will be used throughout the description for the case of simplicity. This does not mean that the invention is restricted to H.323, but equivalent solutions are obtained with the other standards.

There may also be other units in the network, such as a multipoint control unit (MCU) , which enables conferencing between three or more endpoints .

There is a problem with using an analogue telephone. A normal analogue telephone uses numbers as a calling address, according to the ITU-T standard E.164. These telephone numbers can become very long and difficult to remember. It would be a great advantage to be able to use e.g. an e-mail address or similar which often is much easier to remember. That is possible in special IP telephones or similar, but it is not realistic to believe that many would buy an expensive IP telephone just because of that. So how do we find a cheap and flexible solution?

A solution is disclosed according to the invention in Fig. 2. An analogue telephone 10 is connected to a residential gateway 11. Further, there is a calling device 12 that also is connected to the residential gateway 11. The calling device 12 can then be used as an alternative way of call addressing, as will be described below.

The residential gateway 11 may include different modules, whereof an example is disclosed in Fig. 2. For an outgoing signal, an analogue voice signal from the telephone 10 goes into an A/D interface 14, where the analogue voice signal is converted into a digital signal, e.g. a pulse code modulated signal (PCM) . The outgoing signal then enters an echo canceller 15, which cancels any echo in the outgoing signal e.g. by comparing voice data received from the network with voice data transmitted to the network. The outgoing signal then enters an address selector 16 that will be described in more detail below.

Then the outgoing signal enters a voice activity detector 25 and then a voice codec module 17. The voice activity detector 25 monitors the outgoing signal for voice activity. When no activity is detected for a configured period of time, information is sent to a packet protocol module 18, which is described in more detail below. In this way bandwidth may be saved by not transmitting silence. The voice codec module 17 e.g. compresses the outgoing signal.

Last the outgoing signal enters said packet protocol module 18, which encapsulates the outgoing signal for end-to-end transmission in packets with added headers. A header may e.g. include the following protocols: RTP (Real-time Transport Protocol) , UDP (Universal Data Protocol) and IP (Internet Protocol). If the packets are to be sent over e.g. Ethernet, then additional Ethernet data is added to the header. The packets are then transmitted over the packet switched network and are received in the other end.

An incoming signal in the form of packets enters the packet protocol module 18, which removes the headers from the packets. The packets are also stored in a jitter buffer 19. Jitter is a variable interpacket timing caused by the network that the packets traverse. Removing jitter requires collecting packets and holding them long enough to allow the slowest packets to arrive in time to be played in the correct sequence. This causes an additional delay.

The incoming signal then enters a second voice codec module

20, where e.g. decompressing of the incoming signal takes place. The incoming signal then enters a packet loss manager

21, which compensates for lost packets. Last, the incoming signal enters the A/D interface 14, which converts the incoming signal to an analogue signal that the telephone 10 can understand. The A/D interface 14 also generates a ringing signal when a new call comes in.

The exact design of the residential gateway 11 is not of importance for the present invention, which concentrates on the call addressing issue.

The address selector 16 is used when a caller wants to make a call to a callee. If the caller uses the analogue telephone 10, call addressing is obtained by dialling a telephone number according to E.164 as a call address. Then different kind of pulses or similar are created, depending on if it is a telephone with dial or with push buttons. The latter normally follows the standard DTMF (Dual Tone Multi- Frequency) . This is detected by the address selector 16 as an attempt of call addressing from the telephone 10, so detection and analysis are performed in a terminal call addressing module 22 to see what telephone number has been dialled. Then this telephone number will be translated to a network address with the aid of a gatekeeper or similar and a connection can be set up to a telephone or other terminal of the callee.

A more detailed example of the call addressing using H.323 would look like this, see Fig 3: When the residential gateway 11 is connected to the packet switched network 45 it must first register at a gatekeeper 41 in the network, by making a RRQ (Register Request) message. The RRQ contains information about the residential gateway 11, such as e.g. network address (e.g. IP number), port numbers, E.164 number

(telephone number), H.323 alias, e-mail address etc. This is either accepted by the gatekeeper 41 with a RCF

(Registration Confirm) or rejected with a RRJ (Registration

Reject) . When the residential gateway 11 is registered, it is then available for incoming and outgoing calls.

If a caller wants to make a call to a callee, he will pick up the receiver on his telephone 10, which telephone can be seen as being located in a circuit switched network 46. Then the caller will dial a telephone number, i.e. a call address of e.g. the E.164 format to a called terminal 44, such as a telephone, of the callee. The residential gateway 11 will then collect the digits in the telephone number and send an ARQ (Admission Request) containing the telephone number to a gatekeeper 41 in a packet switched network 45.

The gatekeeper 41 has information about registered terminals and will - if possible - translate the E.164 address into a network address that the residential gateway 11 can connect to, i.e. e.g. to an IP number and a port number. The gatekeeper 41 will then respond with either an ACF (Admission Confirm) including said IP number and port number or an ARJ (Admission Reject) if the gatekeeper 41 cannot translate the E.164 address.

The residential gateway 11 can now connect to the called terminal 44 - either directly or via the gatekeeper 41. In the example in Fig. 3 the called terminal 44 is connected to a network gateway 42 out in a circuit switched network 47, optionally via one or more local exchanges 43 or similar. Of course, said network gateway 42 can be a residential gateway as well, or else part of the called terminal 44.

The residential gateway 11 and the network gateway 42 can now negotiate what type of RTP (Real-time Transfer Protocol) stream that will be set up, i.e. port-number, voice compression, frame length etc. The negotiated RTP stream will be set up, which will then transport voice signals in both directions during the call.

Call addressing using SIP will be made in a corresponding way, but messages and means will have other names.

The gatekeeper 41 may be programmed to translate any string - e.g. an e-mail address - into a network address, which opens up other possibilities of call addressing.

A simpler way of call addressing can be made by using the calling device 12 in Fig. 2. The call address is written on the calling device 12 as a string and sent to the gateway 11. The call address can be written in any form, but an e- mail notation is preferred because it is easy to remember. The call address is written on the calling device 12 and the input string is stored in a text module 30. The string will be sent to the address selector 16 in the gateway 11 by pressing a "send" button 28 or corresponding of the calling device 12. This call address is detected by the address selector 16 as an attempt of call addressing from the calling device 12, so detection and analysis are performed in a calling device call addressing module 23 to see what call address was sent. Then this call address will be translated to a network address with the aid of a gatekeeper 41 or similar, see Fig. 4, in a corresponding way as the telephone number was translated according to the description for Fig. 3. Naturally, the gatekeeper 41 must be programmed to be able to understand such a call address. A connection can then be set up to a called terminal 44 in the same manner as in Fig. 3.

The address selector 16 will be able to handle both incoming and outgoing calls under different circumstances. For outgoing calls it will handle following scenarios and with the corresponding actions. If the telephone 10 is offhook and there is no ongoing calls the address selector 16 will dial the callee directly and the gateway 11 will play dial tones to the telephone 10. If there is an ongoing call the address selector 16 can decide to connect to the new callee as well and create a telephone conference. If the telephone 10 is onhook the gateway 11 could for example generate ring tones to the telephone 10 as an instruction for the end-user to pick up the telephone 10. As soon as the telephone 10 goes off-hook the gateway 11 will place the call.

The calling device 12 can also be used for incoming calls. The calling device 12 can present the call address of the caller, e.g. like number presentation in the ordinary PSTN network. In a PSTN network that is utilising DTMF CLIP (Calling Line Identification Presentation) , which is an ETSI standard, the PSTN can only present telephone numbers when there is no ongoing calls. The calling device 12 will not have this limitation and can present call addresses even during a call, e.g. if a second caller tries to call during an already established call. The calling device 12 can also be used for different types of services, in PSTN called CLASS 5 services.

Now, it might happen that someone is dialling on the telephone 10 at the same time that someone is call addressing from the calling device 12. Then the selector 16 has to select which call address is going to be used for the call. Normally the pulses from the analogue telephone will be sent one digit at the time, while the call address from the calling device 12 will be sent in sequence after having pressed the button "send" or similar.

A normal selection could be that if the address selector 16 has begun receiving call address signals from one direction it should stop listening in the other direction, i.e. e.g. after having received one digit from the telephone 10 the signals from the calling device 12 are blocked. When the call is placed the address selector 16 can continue to listen for more addresses, e.g. to initiate telephone conference or other services that includes addressing during calls.

The easiest way for the calling device 12 to communicate with the residential gateway 11 is of course over a cable. However, it could be more advantageous, as is shown in Figure 2, to use a wireless connection, i.e. to have a radio interface 24, 29 in both the calling device 12 and the residential gateway 11. This is particularly advantageous when the user lives in a house or apartment where there are several telephones using the same telephone number and being connected to the same residential gateway 11. In this case the same calling device 12 can be used for initiating a call from any of said telephones. For greater ease the calling device may then be integrated in another device such as e.g. a remote control or a watch. The simplest calling device could be small keyboard 26 on which the call address can be written, an optional display 27 to show the written call address and a "send" button 28 or similar to send the call address to the residential gateway 11. An alternative is to have only a touch sensitive display with a virtual keyboard and/or a virtual send button or similar on it. A further example is to have an address book module 31 included so that it is not necessary to type the whole call address, but only to choose an already registered call address, e.g. in a scroll menu or on a button.

More advanced features can be made by the addition of one or more application modules 32. These features could be to be able to set up conference calls, to program call forwarding, to display the number or ID of someone calling etc, which today often requires that you remember strange number codes when said features are to be used from an analogue telephone. Of course it is also possible to add the feature to be able to choose to instead use the call address to send an e-mail, SMS or similar to someone, by the use of an e- mail module or SMS module as application module.

The example in Fig. 2 concerns an analogue telephone. However, the solution works also with e.g. a digital telephone of ISDN (Integrated Services Digital Network) type. In this case the analogue to digital conversion is of course not needed and the dialled digits will have another format, which requires another type of telephone call addressing module, but otherwise it will work in the same way as the solution in Fig. 2.

Further, even though this description has mentioned mainly telephones, the same solution may of course be used also for other terminals than telephones, such as fax machines or computers handling video sessions and other applications. The only difference is then that "off-hook" is made in another manner than lifting a receiver.

This also means that even though this description has mentioned mainly audio/voice, e.g. video and similar may be handled in the same way as audio/voice, e.g. for a video session.

Claims

1. Calling device (12) for packet switched telephony, c h a r a c t e r i s e d in that the calling device (12) is arranged to send a call address to an address selector (16) in a residential gateway (11) , said residential gateway (11) being arranged to work as an interface between a circuit switched network and a packet switched network.

2. Calling device (12) according to claim 1, c h a r a c t e r i s e d in that the calling device (12) includes a text module (30) arranged to receive a written text for transmission as the call address to the residential gateway (11) .

3. Calling device (12) according to claim 1 or 2, c h a r a c t e r i s e d in that the calling device (12) includes an address book module (31) arranged to store call addresses and arranged to retrieve a chosen call address at command for transmission to the residential gateway (11).

4. Calling device (12) according to any of the claims 1 to

3, c h a r a c t e r i s e d in that the calling device (12) includes an application module arranged to provide access to telephone services such as call forwarding or conference calls .

5. Calling device (12) according to any of the claims 1 to

4, c h a r a c t e r i s e d in that the calling device (12) includes an application module arranged to provide messaging services such as e-mail or SMS.

6. Calling device (12) according to any of the claims 1 to 5, c h a r a c t e r i s e d in that the calling device (12) includes an application module arranged display the number or ID of an incoming call.

7. Calling device (12) according to any of the claims 1 to 6, c h a r a c t e r i s e d in that the calling device includes a display (27), a keyboard (26) and a send button (28) .

8. Calling device (12) according to any of the claims 1 to 7, c h a r a c t e r i s e d in that the calling device (12) includes a radio interface (29) for communication with the residential gateway (11) .

9. Residential gateway (11) for telephony, arranged to work as an interface between a circuit switched network and a packet switched network, c h a r a c t e r i s e d in that the residential gateway (11) includes an address selector

(16) arranged to select between receiving a call address from a terminal (10) in the circuit switched network or from a calling device (12) .

10. Residential gateway (11) according to claim 9, c h a r a c t e r i s e d in that the residential gateway

(11) includes a terminal call addressing module (22) arranged to analyse a call address from the terminal (10) and includes a calling device call addressing module (23) arranged to analyse a call address from the calling device

(12) .

11. Residential gateway (11) according to claim 9 or 10, c h a r a c t e r i s e d in that the address selector (16) is arranged to listen for a call address from the direction of the terminal (10) and from the direction of the calling device (12) simultaneously until the receipt of the beginning of a call address from one of the directions, in which case the address selector (16) is arranged to only listen in said direction.

12. Residential gateway (11) according to any of the claims 9 to 11, c h a r a c t e r i s e d in that the residential gateway (11) further includes a packet protocol module (18) arranged to use the call address that the address selector (16) has selected for setting up a call.

13. Residential gateway (11) according to any of the claims 9 to 12, c h a r a c t e r i s e d in that the residential gateway (11) includes a radio interface (24) for communication with the calling device (12) .

14. System for packet switched telephony c h a r a c t e r i s e d in that the system includes a calling device (12) according to any of the claims 1 to 8 and a residential gateway according to any of the claims 9 to 13.

15. Addressing process for setting up a call in a packet switched network using a residential gateway (11) working as an interface between a circuit switched network and the packet switched network, c h a r a c t e r i s e d by

- selecting between receiving a call address from a terminal (10) in the circuit switched network or from a calling device (12) ; and

- using the selected call address for setting up a call.

16. Addressing process according to claim 15, c h a r a c t e r i s e d by

- listening for a call address from the direction of the terminal (10) and from the direction of the calling device

(12) simultaneously; and

- upon receipt of the beginning of a call address from one of the directions, only listening in said direction.