WO2005081553A1

WO2005081553A1 - System and method for routing a telephone call either through a telephone network or through an ip based network to a subscriber

Info

Publication number: WO2005081553A1
Application number: PCT/EE2005/000002
Authority: WO
Inventors: Ivo Remmelg
Original assignee: Remmelg & Pojad OÜ
Priority date: 2004-02-20
Filing date: 2005-02-20
Publication date: 2005-09-01
Also published as: EP1733576A1

Abstract

A telephony system, comprising a fixed-line phone network (such as public switched telephony network (PSTN)) and/or a mobile phone network (such as public land mobile network (PLMN)), and a data network (such as Internet or other IP employed packet switched network). Subscriber to the fixed-line or mobile phone network has both a phone, connected to the fixed-line or mobile phone network, and a voice terminal, connected to the data network. The system uses a fixed-lineor mobile phone number, assigned by the fixed-line or mobile phone network, as a common identifier for both the phone and the voice terminal. Incoming calls to that fixed-line or mobile phone number are connected to the phone or to the phone or to the voice terminal, or both, according to the subscriber's preferences.

Description

SYSTEM AND METHOD FOR ROUTING A TELEPHONE CALL EITHER THROUGH A TELEPHONE NETWORK OR THROUGH AN IP BASED NETWORK TO A SUBSCRIBER

BACKGROUND OF THE INVENTION TECHNICAL FIELD 5 The invention relates to the field of telephony systems, namely to systems comprising a data network and a phone network. Subscriber to the phone network has both a phone, connected to the phone network, and a voice terminal, connected to the data network. The system uses a phone number, assigned by the phone network, as a common identifier for both the phone and the voice terminal so that incoming calls to 10 that phone number are connected to the phone or to the voice terminal, or both, according to the subscriber's preferences.

RELATED PRIOR ART Many people today have several types of communication devices, such as fixed-line 15 phones (or landline phones, both at home and at work), and a mobile phone. It is often necessary to forward calls from one device to another, e.g., calls to a home number are forwarded to an office number or to a mobile phone during the office hours. However, occasionally people forget to forward calls or to cancel call forwarding. In that case, the person cannot be reached. 20 For a mobile phone, an additional problem is that, to activate or to de-activate call forwarding, the mobile phone must be within the mobile network coverage area and the mobile phone must be switched on. Therefore, it is impossible to use call forwarding, e.g., when the mobile phone's battery is empty and there is no alternative 25 source available or when something happens to the mobile phone itself (e.g., a technical failure or the mobile phone is stolen). Also, usually, the person forwarding calls pays for such calls and thus, call forwarding can be expensive, particularly when calls to mobile phone are forwarded to fixed-line phone or from fixed-line phone to mobile phone. Therefore, there is a necessity to provide an alternative solution to call 30 forwarding. Even though mobile phones are often more user friendly compared to fixed-line phones, they also have some disadvantages. The call is charged per minute and the rate is usually higher than for the fixed-line phone. The number of concurrent calls within a single cell of a mobile network is limited as the number of available communication channels is limited. Too many users trying to make simultaneous calls overload the mobile network, making the service unavailable. The only solution is to reduce the size of the cell so that the channels can be reused. Also, the quality of mobile phone connection might be unacceptable due to difficult or peculiar environmental conditions (i.e., in valleys or in contemporary buildings, made of steel and reinforced concrete that cannot be passed through by mobile signals). Therefore, there is a need for alternative methods of communications to reduce the likelihood that the mobile network is overloaded and to improve the quality of service.

It is a common practice to use private branch exchanges (PBX) within a company to provide employees with phone services. Main functionalities of PBX include free calling between users connected to the PBX, the calls can be easily transferred from one user to another (there are number of other functionalities available). However, PBX needs maintenance and it camiot be easily expanded or expanding can be costly.

As distinct from the voice over circuit switched networks (such as public land mobile network, or PLMN, and public switched telephony network, or PSTN), real time voice information can also be delivered over packet switched network, such as networks based on IP protocol (LAN, WAN or Internet). Voice transmission over such networks, which is called "Voice over IP" (VoIP) is coming more and more widespread. In such networks, the subscribers are addressed via addresses that conform to the Internet Protocol, including Internet addresses and E-mail addresses. Thus, a subscriber to a VoLP service can be reached only if the caller knows her address.

There are usually more than one mobile network operator in any geographical area (e.g., a country or state). There must be at least one mobile network infrastructure (i.e., antennas, switching centers, gateways to other networks and other devices) so that one or more network operators could provide services to their subscribers. Usually, there are no more than 2 to 3 competing mobile networks (infrastructures) in every geographical area, whereas the number of service providers can be higher. Those service providers who do not have their own mobile network infrastructure, can buy network resources (i.e., calling time) in bulk and resell these resources to their own subscribers. Such service providers are also called virtual operators.

An operator is required by law to allow their subscribers to call the subscribers of other operators, as well as to allow subscribers of another operator to call their subscribers. In these cases, the call is initiated in one mobile network and then transferred to another mobile network. Such calls are more expensive compared to those completely in one network.

Not all the networks cover the territory equally. Therefore, a subscriber of one operator may travel to a location where her operator has no network, but the competitor has. Such subscriber may still use her mobile phone if the competitor has agreed to serve the subscribers of the first operator. Usually, calls made while outside the home network (also called roaming) are more expensive.

Roaming is typical while traveling abroad as very few operators have networks covering several countries. The cost per minute while roaming can be ten times or more higher than the cost in home network. Also, often not only the caller is charged for a call, but also the person answering the call. Therefore, there is a necessity for more economic way of making calls while traveling.

Systems exist for transmitting calls from a mobile network to an alternative network, such as Internet, using, e.g., H323.1 standard. Naqvi et al US patent No. 6625449, filed 22 November 2000, issued 23 September 2003 for System and method of siphoning message from a mobile network to an alternative network discloses a system where the call is intercepted to a public switched telephony network or

Internet from the level of base station subsystem (BS), even before the call reaches a mobile switching center (MSC). This system is not suitable to achieve the objectives of the invention. First, the call is intercepted before it enters the call metering unit, i.e., the length of the intercepted camiot be measured. Thus, the solution is not suitable for virtual operators. Also, each mobile network contains several mobile switching centers (MSC), and therefore, several gateways are needed to connect mobile network and alternative networks. Also, the system does not allow determining whether the subscriber can accept calls in the data network, e.g., whether the subscriber is connected to the data network.

BRIEF SUMMARY OF THE INVENTION - DISCLOSURE OF INVENTION An objective of the invention is a telecommunication systems for transferring calls between a fixed-line phone network (such as public switched telephony network (PSTN)) or in a mobile phone network (such as public land mobile network (PLMN)), and a data network (such as Internet or other IP employed packet switched network), whereas the phone network subscriber has a phone, connected to the phone network, and a voice terminal (such as, e.g., PC with sound card, microphone and earphones), connected to a data network, so that the subscriber can answer incoming calls either in the phone network or in the data network, depending on subscriber's preferences.

Such system reduces calling and roaming costs, provides an additional communication channel for virtual operators and reduces call load in cell that are most overloaded (e.g., in urban areas). System also allows to group subscribers into virtual user groups composed of subscribers of one or several phone operators or to provide virtual PBX (centrex) services.

Fixed-line phone networks (hereinafter fixed-line network) and mobile phone networks (hereinafter mobile network) are connected together into one system, using gateways between networks. Each user of the system is a subscriber to a fixed-line network or mobile network, or both. Each user also has a voice terminal, connected to the data network. The system transfers calls, according to the predefined rules, designated to subscriber's fixed-line number or mobile phone number to her voice terminal. The user can answer the call using voice terminal instead of mobile phone or fixed-line phone. Also, the user can initiate a call using her voice terminal, whereas the system shows her fixed-line or mobile phone number as caller ID. Additionally, the system allows to share the operator the call termination fees with the user answering calls through data network thanks to the less networks involved within the call path.

Another objective of the invention is a method for terminating calls in a system according to present invention. The method comprises the following steps: sending a ringing indication to a mobile switching center; forwarding subscriber's number to the database, storing in the database a data network address of the voice terminal at the time the voice terminal is connected to the data network; and mapping the data network address with the subscriber's number; determining the data network address from the database according to the subscriber's number and terminating the call through the first gateway to the subscriber's voice terminal.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig 1 depicts the invention according to first embodiment, whereas the system comprises both fixed-line and mobile networks

Fig 2 depicts another embodiment of the invention, whereas one fixed-line network and one mobile network is connected to the system.

DETAILED DESCRIPTION OF THE INVENTION

Figure 1 depicts a system 1 according to one embodiment. System comprises gateway 2, switch 21, database 22 (which can be a part of the switch). Mobile networks 6 and 7 and fixed-line network 13 (operated by the same or different operators) are connected to the system through the gateway (whereas the gateway can be operated by its own operator or be a part of switch in a mobile network or fixed-line network). Connecting mobile networks and fixed-line networks with the gateway is known, e.g., the following standards could be used: Qsig, ISDN, -SS7/C7 and El and TI data networks can be used.

Also a mobile network 8 is shown in Figure 1, but it is not connected to the system. However, it is connected with mobile networks 6 and 7, using standard methods, whereby its subscriber can use her mobile phone 10 for calling the subscribers of other fixed-line or mobile networks.

Each mobile network 6, 7 and 8 comprises at least one mobile base station 61, 71 and 81 that provide mobile network coverage area. Mobile network 6 has subscribers 3, 4 and 5 who can use their mobile phones 31, 41 and 51 in their home network (mobile network 6). Mobile network 7 also has subscribers but they are not shown on Fig. 1. Subscriber 5 is outside her home network 6 and is using her mobile phone in mobile network 7 (there must be an agreement in place between the operators of mobile networks 6 and 7).

Traditionally, to make a mobile phone call, a subscriber within the coverage area dials a number, the number is forwarded to a mobile switching center, the location of the recipient is determined from Home Location Register (HLR) and connected to a recipient if the recipient is within the coverage area. If both persons are within the same network and subscriber of the same operator, then the call is completed within a single network. If either caller or the recipient is outside the network, then the call is completed in cooperation with at least two operators.

The system according to present invention is operated as follows. Subscribers 3, 4 and 5 are subscribers of mobile network 6 and also can use the functionalities of the gateway 2 and switch 21. They can use their mobile phone 31, 41 and 51 as usual while within the mobile network 6. They can also call the users of other mobile networks, however, such calls are more expensive, particularly when the receiver is roaming abroad. Subscribers 3, 4 and 5 also have voice terminals 32, 42 and 52 for having voice conversations over data network 3. Data network can be any packet-switched network, such as Internet or other IP employed network. Voice terminals can be personal computers with sound cards, microphones and earphones (speakers), IP handsets that be connected to the computer, e.g., using USB port, or special IP phones (also known as VoIP phone, WiFi phone).

In this application, voice terminal (such as 32) and mobile phone (31) together are called a subscriber terminal group.

Gateway 2 converts the voice signal from the phone networks so that it can be transferred in a data network (e.g., using SLP, H323 or MGCP standards). Time- division multiplexing may be used in the phone networks, so TDM-IP gateways are used. Such gateways are produced by e.g., RADirect, www.ra-direct.com and Audiocodes, www.audiocodes.com. The IP addresses of voice terminal 32, 42 and 52 are entered into a database 22 while the voice terminal is connected to the data network (note that signaling is shown by thin line whereas the payload is shown by thick line). A call is connected through switch 21 to the voice terminals according to the information, stored in the database. Call may be connected either to a voice terminal only or to both voice terminal and telephones (i.e., mobile phones, such as 31, or fixed-line phones, such as 14).

For all the callers, the subscriber is identified by mobile network of fixed-line network subscriber number (i.e., so-called El 64 number, e.g., the number assigned by mobile network 6 and associated with mobile phones 31, 41 and 51). For that, the subscriber number is stored in the database 22 together with the IP address of the IP phone (there may be existing other methods for identifying voice terminals in the data network like username and password based registration).

The system allows the operator of the gateway 2 (and switch 21) to provide additional services. For example, operator can group subscribers 3, 4 and 5 into virtual user group 12. A data network, such as local data network 11 (LAN, WiFi or Bluetooth network) or WAN or Internet 9 is used to make calls within the virtual user group. All PBX like services, such as voicemail, call forwarding, call waiting, caller ID, call hold, call screening, call blocking, abbreviated numbers, call logs, etc, are available for such subscribers. Also, members of the virtual user group 12 can, using special user interface, see the status of other members of the group, e.g., whether they are online, offline, busy, etc.

Another embodiment of the invention, a modification of a system of Fig 1 is depicted on Fig 2. System 100 comprises switch 121, gateways 123 and 124, database 122 (whereas the switch, the gateways and the database can all be accomplished as one single device, or comprising several independent modules, or gateways can be part of the mobile network 106 or fixed-line network 113). A mobile network 106, a fixed- line network 113, and a data network 103 is connected with the system. Mobile network 106 comprises mobile base stations 107 and 108. Mobile network subscribers have mobile phones 109 and 110. Subscribers of fixed-line network 113 have fixed-line phones 112 and 114. Mobile network 106 and fixed-line network 113 are connected with a communication channel 115 (showed as dotted line in Fig 2) so that the subscribers of the mobile network can call the subscribers of the fixed-line network and vice versa (connecting networks using a communication channel 115 is well known from the prior art). A voice terminal 111 (similar to voice terminals 32, 42 and 52 in Fig 1) is connected to the data network.

Mobile phone 110, voice terminal 111 and telephones 112 all belong to the same person. This way, that person can choose which device to use for initiating a call. Similarly, that person can choose any of these devices for answering a call.

Database 122 is used to store different types of information, such as whether the voice terminal 111 is connected to the data network (i.e., having connected status) or not (i.e., having disconnected status), the status of the terminal (i.e., whether the person is away, busy, wishes not to be disturbed, etc.). Also, subscriber mobile phone number and fixed-line phone number are associated with the address (MAC or IP address) of her voice terminal. The system is typically operated as follows. A subscriber of mobile network 106 initiates a call, using mobile phone 109, dialing number of the mobile phone 110 or fixed line phone 112, all belonging to the subscriber terminals group of subscriber 130. The call (or its signaling) is connected through the mobile station 107 through the mobile network 106 to the gateway 123 and is put on hold. An inquiry is into database 122 is made as whether the voice terminal 111 of the called subscriber 130 is connected to the data network 103 and whether the subscriber is accepting calls on that device. If the voice terminal 111 is connected to the data network 103 and the subscriber has not chosen not to accept calls on that device, the call is connected through the gateway 123, switch 121 and data network 103 to the voice terminal 111.

Similarly, a subscriber of fixed-line network 113 initiates a call, using telephone 114, dialing number of the mobile phone 110 or fixed-line phone of the subscriber 130. The call (or its signaling) is connected through the fixed-line network 113 to the gateway 124 and is put on hold. An inquiry is made into database 122 as to whether the voice terminal 111 is connected to the data network 103 and whether the subscriber is accepting calls on that device. If the voice terminal 111 is connected to the data network 103 and the subscriber has not chosen not to accept calls on that device, the call is connected through the gateway 124, switch 121 and data network 103 to the voice terminal 111.

If the voice terminal is not available or if the subscriber has preferred receiving calls on her mobile phone 110 or her fixed-line phone 112, then the call is connected through gateway 123, through mobile network 106 and mobile station 108 to mobile phone 110, or through gateway 124, fixed-line network 113 to fixed-line phone 112, respectively. A call from mobile network 106 to fixed-line network 113 can be routed through the communication channel 115 or alternatively, through the system according to present invention (i.e., mobile network 106 to gateway 123 to gateway 124 to fixed-line network 113). The call, initiated in the mobile network 106 or fixed- line network 113 does not need to be transferred two times through the gateway 123 or 124 respectively if the subscriber 130 prefers answering the call within the network where call was initiated. Signaling information can be exchanged in between switch 121, database 122 and the mobile network 106 and fixed-line network 113 according to the existing signaling methods.

The user of voice terminal 111 can choose, whether her mobile phone 110 number or telephone 112 number is associated with outgoing call. The chosen number is shown as user's caller ID for outgoing calls.

The invention has several advantages. The subscriber can receive phone calls, dialed to her mobile subscriber number, on her PC or IP phone in any geographical location with data network connection. Transferring calls from the mobile network to the data network allows to reduce load in mobile network, particularly in crowded cells, and to provide better quality in the areas of insufficient signals.

There are additional advantages for subscribers of different mobile networks.

Traditionally, calls between these subscribers are more expensive for both the caller and for the recipient as the service is provided by more than one operator. In the system according to the invention, only one mobile network is used when the recipient answers the call on her voice terminal instead of using mobile phone as in this case, the call stays within the home network.

There are more advantages for subscribers, traveling in the coverage area of another mobile network. Traditionally, to use mobile services, there must be a roaming agreement in place between mobile network operators. According to invention, the recipient can use her voice terminal to receive phone calls and thus, avoid roaming charges.

Subscribers can be connected to the data network in a number of ways, e.g., using dial-up modems, or broadband services, such as ADSL, cable or ISDN modems, through corporate LAN, having connection to the Internet. The system may be used within wireless Internet coverage area (such as WiFi, IEEE 802.1 In, WiMax, IEEE 802.16, or Bluetooth, SIG or IEEE 802.15.1). Devices having dual functionalities as mobile phones and voice terminals (such devices include NEC (N900iL), Hewlett Packard (HP 6315iPaq) and Motorola (CN620)) can be used. Such device is periodically checking whether the wireless data network is available and whether the subscriber has access rights. If so, the call can be seamlessly transferred from mobile network to data network, thus reducing the costs.

A method for terminating calls in a system according to present invention is also disclosed. The method comprises the following steps: sending a ringing indication for a call initiated in the mobile network to a mobile switching center; and forwarding a subscriber's number to the database, storing to the database a data network address of the voice terminal at the time the voice terminal is connected to the data network; and mapping the data network address with the subscriber's number; determining the data network address from the database according to the subscriber's number and terminating the call through the first gateway to the subscriber's voice terminal. Also, the call addressed to the user is connected to both the subscriber's voice terminal and subscriber's phone terminal. Furthermore, subscriber's preferences can be stored in the database and the call can be according to the subscriber's preferences, retrieved from the database. Method may additionally comprise a step of determining subscriber's preferences according to predetermined parameter, such as cost to the subscriber.

The exemplary embodiments presented herein illustrate the principles of the invention and are not intended to be exhaustive or to limit the invention to the form disclosed; it is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.

Claims

1. Telephony system, comprising a mobile network and a data network, a first gateway for intercomiecting the mobile network with the data network, the mobile network having at least one subscriber, using a mobile phone in the mobile network, and a voice terminal connected to the data network, characterized in that the voice terminal and the mobile phone of the mobile network subscriber are paired up, composing a subscriber terminal group, the voice terminal is selectively connected to the data network, thus the voice terminal having at least a first, connected status and a second, disconnected status; the system comprises a database for storing the statuses of the voice terminals; and a switch between the mobile network and the data network, whereas a call to the subscriber of the data network is connected through the gateway to the voice terminal only when the voice terminal has a connected status according to the database.

2. System according to claim 1, characterized in that the system additionally comprises a second gateway for interconnecting a fixed-line network with a data network; and a fixed-line phone, used by the subscriber of the subscriber terminal group, and connected to the fixed-line network.

3. System according to claim 1 to 2, characterized in that the subscriber terminal group additionally comprises the fixed-line phone.

4. System according to claims 1 to 3, characterized in that the subscriber terminal group is identified by the subscriber's mobile phone number.

5. System according to claims 1 to 4, characterized in that a VOIP/PLMN handset is used as the subscriber terminal group.

6. System according to claim 5, characterized in that the VOIP/PLMN handset has wireless IP connectivity.

7. System according to claim 1 to 4, characterized in that the voice terminal is an IP phone.

8. System according to claim 1 to 4, characterized in that the voice terminal is a personal computer with IP phone software.

9. Method for terminating calls in a system, comprising a mobile network, comprising a mobile switching center; a data network; a gateway for interconnecting the mobile network with a the data network; mobile phone connected to the mobile network and used by a subscriber and at least one voice terminal selectively connected to the data network, and used by the subscriber, a database for storing number of phone subscriber numbers the method comprising the following steps: sending a ringing indication for a call initiated in the mobile network to a mobile switching center; and forwarding a subscriber's number to the database, characterized in that the method additionally comprises the following steps: storing to the database a data network address of the voice terminal at the time the voice terminal is connected to the data network; and mapping the data network address with the subscriber's number; determining the data network address from the database according to the subscriber's number and terminating the call through the first gateway to the subscriber' s voice terminal.

10. Method according to claim 9, characterized in that the call addressed to the user is connected to both the subscriber's voice terminal and subscriber's phone terminal.

11 Method according to claim 10 characterized in that the method additionally comprises the steps of recoding subscriber's preferences in the database and connecting the call to the subscriber's voice terminal or mobile phone according to her preferences, retrieved from the database.

12. Method according to claim 11, characterized in that the method additionally comprises the step of determining subscriber's preferences according to predetermined parameter.

13. Method according to claim 12, characterized in that the predetermined parameter is a cost of the call to the subscriber.