WO2012163659A1

WO2012163659A1 - Gsm handset, connection server and method for establishing a phone call

Info

Publication number: WO2012163659A1
Application number: PCT/EP2012/058895
Authority: WO
Inventors: Kurtulus ORKUN
Original assignee: Orkun Kurtulus
Priority date: 2011-05-27
Filing date: 2012-05-14
Publication date: 2012-12-06

Abstract

A GSM handset(10) is provided having a telephone number with a country code corresponding to a first country. The GSM handset comprises a user interface(11), a GSM transceiver (13) and a processor (12). The user interface (11) is provided for receiving, from a user, a telephone number of a destination telephone (31,32) having a telephone number with a country code corresponding to a second country. The GSM transceiver (13) is provided for communicating with other GSM transceivers using the GSM standard. The processor (12) is coupled to the user interface (11) and the GSM transceiver (13) and is arranged to analyze the received telephone number to determine whether the second country differs from the first country. If it is determined that the second country differs from the first country, the processor (12) controls the GSM transceiver (13) to call a connection server (21) in the first country, to send the telephone number of the destination telephone (31, 32) to the connection server (21) and to employ a VoIP connection between the connection server (21) and the destination telephone (31,32) to establish a telephone call between the GSM handset (10) and the destination telephone (31, 32).

Description

GSM handset, connection server and method for establishing a phone call

Field of the invention

This invention relates to a GSM handset having a telephone number with a country code corresponding to a first country, the GSM handset comprising a user interface for receiving, from a user, a telephone number of a destination telephone having a telephone number with a country code corresponding to a second country, a GSM transceiver for communicating with other GSM transceivers using the GSM standard, a processor coupled to the GSM transceiver and being arranged to control the GSM transceiver to establish a telephone call between the GSM handset and the destination telephone.

This invention further relates to a connection server for establishing this telephone call and a telecommunication system comprising the GSM handset and the connection server.

The invention also relates to the methods to be performed in the GSM handsets and the connection server for establishing the call and to computer program products for causing processors to perform said methods.

Background of the invention

GSM is a 2G (2^nd generation) mobile telecommunication standard used for setting up calls with other wireless or landline telephones employing the public switched telephone network (PSTN). Over the last decades, GSM has become the de facto standard for wireless mobile phone calls. As a result GSM subscriptions are relatively inexpensive. However, when using GSM for making international phone calls, the costs increase significantly. This is mainly due to the high prices GSM providers charge other GSM providers for making use of their nationally implemented telecommunication

infrastructure. Especially in Europe, where countries are not so large and many people and businesses need to make international phone calls on a regular basis, the costs of international calls may be a serious problem. In some countries, also national calls to GSM telephones using a different GSM provider may be very expensive. Away of avoiding these high costs for international phone calls (and/or some national phone calls), many people use VoIP (Voice over IP) solutions such as Skype. VoIP calls use the Internet for setting up conversations between two or more people instead of the PSTN. VoIP applications send and receive IP data packets between the participants in the conversation. The data packets may comprise audio, video and/or text data. Because the Internet is a worldwide network without any territorial restrictions, users do not have to pay more for international calls than for national ones. The only costs that have to be paid are the costs for the Internet connection and, possibly, for the amount of data that is transmitted. VoIP applications use usernames instead of telephone numbers for addressing other parties. A disadvantage of using VoIP technology is that all parties to the conversation require an available Internet connection with sufficient bandwidth for transporting all data. In a home or office environment that may not be a problem, but many mobile phone users do not yet have constant broadband internet access. Many mobile phones nowadays use 3G technology, e.g. UMTS, for connecting to the Internet. However, reliable mobile broadband Internet access is not as widespread as access to the GSM or other 2G networks. VoIP tools may therefore not always be usable, the reliability of the connection may be a problem or sound quality of the call may be inferior. Some telecommunication providers charge additional fees for using high data loads and/or VoIP services. Other telecommunication providers even block VoIP related data transfer in order to prevent overload of the communication network or to prevent income loss due to a reduced use of the GSM network for international (and national) telephone calls.

To avoid the problem of the other party having to be connected to the Internet, some VoIP to GSM solutions are available. For example, Skype allows its users to use their IP application for calling a (mobile or landline) telephone number over the Internet. The user employs his Internet connection to contact a Skype connection server. The connection server than uses the PSTN to make contact with the telephone of choice. This solution, however, still has most of the disadvantages of the pure VoIP connection (availability, reliability, data load) and requires the user to pay additional fees to Skype for the use of this VoIP to PSTN service.

Object of the invention

It is therefore an object of the invention to provide a more reliable and, if possible, cheaper way of calling a telephone in a different country. Summary of the invention

According to a first aspect of the invention, this object is achieved by providing a GSM handset having a telephone number with a country code corresponding to a first country, the GSM handset comprising a user interface, a GSM transceiver and a processor. The user interface is provided for receiving, from a user, a telephone number of a destination telephone having a telephone number with a country code corresponding to a second country. The GSM transceiver is provided for communicating with other GSM transceivers using the GSM standard. The processor is coupled to the user interface and the GSM transceiver and is arranged to analyze the received telephone number to determine whether the second country differs from the first country. If it is determined that the second country differs from the first country, the processor controls the GSM transceiver to call a connection server in the first country, to send the telephone number of the destination telephone to the connection server and to employ a VoIP connection between the connection server and the destination telephone to establish a telephone call between the GSM handset and the destination telephone.

The main advantage of the GSM handset according to the invention is that the handset only needs the local GSM (or a similar 2G) communication system for setting up a call with someone in a different country. However, no expensive international GSM call is needed. When the processor analyzes the telephone number and sees that an international call is requested, the processor automatically diverts the call to a local connection server within the first country. International calls are easily identified based on the country code of the destination telephone number. For example, when calling from a Dutch GSM handset (telephone number e.g. +31 612345678) to a German destination telephone (e.g. +49 123546789), the processor will know from the country code of the destination telephone number (+49) that the connection should be established via the connection server.

The GSM handset may contact the connection server by calling a fixed telephone number or a random number within a fixed range of telephone numbers. For a fast and reliable connection, the GSM handset may be programmed to use a unique connection server telephone number assigned to the user or GSM handset. In that way, there will always be a connection line available when calling the connection server.

Alternatively, multiple users may share one connection server telephone number and the connection server may forward the call to an available connection line. In a further alternative implementation, the handset tries another telephone number from the fixed range of telephone numbers when the first attempt of contacting the connection server fails due to, e.g., a busy connection line.

When calling the connection server, the processor also controls the GSM transceiver to send the telephone number of the destination telephone. The destination telephone number may be transmitted using dual-tone multi- frequency signaling (DTMF) or other ways of sending data signals that do not require more than just a GSM

connection. For example, SMS text messaging may be used. The connection server then uses this destination telephone number to set up a VOIP connection between the connection server and the destination telephone in a way similar to how a Skype server is able to contact telephones in different countries. Consequently, the GSM handset does not need an Internet connection to take advantage of the benefits of using VoIP for international telephone calls. Also the destination phone on the receiving end does not have to be Internet-enabled.

Together with the telephone number of the destination telephone, the GSM handset may also send some user ID and/or pin code in order to identify himself to the connection server. The connection server may use such information to authorize the GSM handset or user to use this connection service. When authorization is needed to use the system, it is also possible to track how and how much the user uses this service and to make him pay accordingly.

If the GSM handset is used for dialing a telephone number with the same country code as the telephone number of the GSM handset itself, no connection with the connection server is needed. The GSM handset will call the destination telephone directly and no VoIP connection is used at all. One of the main advantages of this invention is that the processor recognizes whether an international phone call is to be made or not. The user can make an international phone call in the same way as he makes his local phone calls. When the processor recognizes the international destination, the required VoIP connection is set up without requiring any further actions from the user.

The connection server may, of course, also be used for local calls. That may, e.g., be an interesting option if calling to a telephone number associated with a different provider would be more expensive than calling a telephone number associated with the provider of the user of the GSM handset. The connection server may be used for all local calls or only for calls to a telephone number of the expensive provider. Like for the recognition of the international telephone calls, the processor of the GSM handset may be able to recognize calls needing such expensive providers by analyzing the destination telephone number. Usually, specific ranges of telephone numbers are assigned to specific providers. Such information may be stored on a storage medium of the GSM handset itself or on a SIM card inserted in the GSM handset. Alternatively, the user may be enabled to select contacts from a contact list, which contacts have to be called with or without using the connection server.

It is to be noted that the GSM handset according to the invention may even make it possible to use the connection server for setting up a call with a destination telephone, not having a telephone number. For example, an IP number, Skype username, MSN username or other type of unique personal identification code may be sent to the connection server. If the connection server recognizes the person that has to be called, the connection server may set up a VoIP connection to the Skype application, MSN application or other VoIP applications of the person to be contacted.

According to a further aspect of the invention, a connection server is provided for establishing a telephone call between a GSM handset having a telephone number with a country code corresponding to a first country and a destination telephone having a telephone number with a country code corresponding to a second country. The connection server comprises a GSM transceiver, a VoIP module and a processor. The GSM transceiver is provided for communicating with other GSM transceivers using the GSM standard and for receiving, from the GSM handset, the telephone number of the destination telephone and a user identification code identifying the user of the GSM handset. The VoIP module is arranged for establishing a VoIP connection between the connection server and the destination telephone. The processor is coupled to the GSM transceiver and the VoIP module and is arranged to analyze the received user

identification code to determine whether the user is authorized to use the connection server for establishing the telephone call. If it is determined that the user is authorized to use the connection server for establishing the telephone call, the processor controls the VoIP module to establish the VoIP connection, and employ the VoIP connection and the GSM transceiver to establish the telephone call between the GSM handset and the destination telephone. An important difference between this connection server and the known Skype server for setting up a connection with a destination telephone is that not only the destination telephone, but also the source telephone is not connected to the Internet.

When the user setting up the call (at the source telephone) uses the Internet to make a connection with the connection server, user IDs, destination telephone numbers, passwords and other information are sent to and processed by the connection server in a straightforward way using IP data packets. According to the invention, the connection server must be arranged to receive the destination telephone number and the user identification code using the GSM communication standard only. The GSM transceiver may, e.g., be arranged to receive and process DTMF or SMS data or other small data packets that can be transmitted using GSM communication means.

According to a further aspect of the invention, a telecommunication system is provided comprising a GSM handset and a connection server as described above. It is to be noted that the connection server may also be a network of multiple connection servers positioned in different places and coupled via a wide area network, such as the Internet. When multiple connection servers are used the functionality of the connection server according to the invention may be distributed over the different servers. Preferably a first connection server in the first country, via GSM, provides for all communication with the GSM handset while a second connection server in the second country provides for the communication with the destination telephone. The destination telephone may also be a GSM handset, but could also be a landline phone or a VoIP phone. If the destination telephone is a VoIP phone, it may have a virtual telephone number. Preferably, to avoid high costs for international calls, all non-VoIP

communication between a server and a telephone is provided by a server in the same country as the telephone.

According to a further aspect of the invention, methods to be performed in the GSM handsets and the connection server for establishing the call are provided. Also computer program products for causing processors to perform said methods are part of the invention. These and other aspects of the invention are apparent from and will be elucidated with reference to the embodiments described hereinafter.

Brief description of the drawings

In the drawings: Figure 1 schematically shows a telecommunication system according to the invention,

Figure 2 schematically shows a GSM handset according to the invention, Figure 3 schematically shows a connection server according to the invention, and

Figures 4 and 5 show flow diagrams of methods according to the invention.

Detailed description of the invention

Figure 1 schematically shows a telecommunication system according to the invention. The telecommunication system comprises a GSM handset 10 for enabling a user to make a phone call using the GSM communication standard. Although no UMTS or other type of 3G or 4G Internet access is required for enjoying the benefits of the current invention, the GSM handset 10 preferably is a 3G or 4G enabled smart phone. Having an Internet connection makes it easier to download and update the firmware and/or software of the GSM handset 10. The GSM handset 10 is described in more detail below with reference to figure 2.

Via a nearby GSM base station antenna 16, the GSM handset 10 is coupled to a GSM network. The GSM network is used to enable the GSM handset 10 to make phone calls to a destination telephone 31, 32. The destination telephone 31, 32 may either be another GSM handset 31 or a landline phone 32. In order to set up a phone call with the landline phone 32, the GSM network is coupled to the public switched telephone network (PSTN). According to the invention, the normal GSM and PSTN networks are only used for making phone calls to other telephones 31 , 32 in the same country.

When the GSM handset 10 analyzes a phone number entered by the user and finds out that an international call is to be made, the GSM handset 10 does not call the destination telephone 31, 32 directly via the GSM/PSTN network. Instead, the GSM handset 10 makes a call to a connection server 21. Below, with reference to figure 4, it is explained how this call to the connection server 21 is made. Figure 3 shows details of the connection server 21. The connection server 21 receives the call from the GSM handset 10. The connection server 21 further receives the destination telephone number which is preferably sent to the connection server 21 as a DTMF signal. Alternatively, a separate SMS text message may be sent to the connection server 21. In a preferred embodiment, the GSM handset 10 also sends a user specific identification and/or security code to the connection server 21 (e.g. via DTMF or SMS). The connection server 21 can recognize the GSM handset 10 by its telephone number. This telephone number may be used for identifying the user. Alternatively, different users may take advantage of the inventive connection service using the same phone. In that event, a user identification code should be used for identifying the user. Using a separate user identification or security code instead of the telephone number only, also helps against spoofing (pretending to call from a certain telephone number).

The connection server 21 may use the user identification and/or security code to check whether the user is authorized to use the connection service and to enable billing the user for the services received. The billing may, e.g., be realized using a prepaid credit account or a monthly subscription.

The received telephone number of the destination telephone 31 , 32 is used by the connection server 21 to set up a VoIP connection with the destination telephone 31 , 32. If the destination telephone 32 is a VoIP telephone, the connection server 21 may set up a direct IP connection with the destination telephone 32. Alternatively, the VoIP connection may be realized via a further connection server 22 and/or via a GSM/PSTN network. If the GSM/PSTN is to be used in a different country, it may be preferable to use the additional connection server 22 in said country for making the transition from the IP network to the GSM/PSTN network. Together with the set up VoIP connection between the connection server 21 and the destination phone 31, 32, the GSM connection between the GSM handset 10 and the connection server 21 results in an established telephone call between the GSM handset 10 and the destination telephone 31, 32. It is to be noted that this telephone call does not require an Internet connection for the GSM handset 10 and does not require any international GSM/PSTN connection. All borders that have to be crossed can be crossed by the VoIP connection set up by the connection server 21.

Figure 2 schematically shows the GSM handset 10 according to the invention. The GSM handset 10 comprises a user interface 11, a processor 12, a GSM transceiver unit 13 and storage means 15. The user interface 11 may, e.g., comprise buttons 111 for dialing a telephone number and/or a touch screen 112 for allowing a user to manipulate a graphical user interface displayed thereon. The GSM transceiver 13 comprises an antenna 14 for sending and receiving data using the GSM communication standard. According to the invention, the GSM transceiver 13 may, e.g., be used to send the telephone number of the destination telephone 31, 32, a user identification code or a security code to the connection server 21. The GSM transceiver 13 also sends and receives voice data to and from the connection server 21 when the telephone call with the destination telephone 31, 32 is established. The voice data may, of course, comprise more sounds than spoken words only. The storage means 15 may store, e.g., user data, contact data such as telephone numbers or software for operating the GSM handset 10. The storage means 15 may comprise solid state memory, a hard disk or any other suitable element for storing data in electronic form. The user interface 11, the GSM transceiver 13 and the storage means 15 are coupled to a processor 12. The processor 12 is arranged to control the GSM handset 10 to execute the method shown in figure 4.

Figure 3 schematically shows the connection server 21 according to the invention. The connection server 21 comprises a GSM transceiver 23, a processor 24, a VoIP module 25 and storage means 26. The GSM transceiver 23 is, e.g., provided for receiving the data sent by the GSM handset 10 and for sending and receiving voice data to and from the GSM handset 10 when the telephone call with the destination telephone 31, 32 is established. The VoIP module 25 is arranged to make a VoIP connection with other connection servers 22, IP telephones, or interfaces for connecting to the GSM/PSTN network. The storage means 26 may store, e.g., user information, payment information, a billing system, configuration data, network information or software for configuring and operating the connection server 21. The storage means 26 may comprise solid state memory, one or more hard disk or any other suitable elements for storing data in electronic form. The GSM transceiver 23, the VoIP module 25 and the storage means 26 are coupled to a processor 24. The processor 24 is arranged to control the connection server 21 to execute the method shown in figure 5. The connection server 21 is preferably capable of using SS7 or SS7-compatible protocols. The connection server 21 may comprises and use ISDN-, PRI-, T1-, El- or other telecommunication units.

Figures 4 and 5 show flow diagrams of exemplary methods for establishing a telephone call with a GSM handset 10 according to the invention. The flow diagram in figure 4 shows the steps taken by the processor 12 in the GSM handset. The flow diagram in figure 5 shows the steps taken by the processor 24 in the connection server 21. Both methods are preferably executed by software applications running on the respective processors 12, 24. In input step 41, the destination telephone number is received by the processor 12. The destination telephone number is provided by the user via the user interface 11 of the GSM handset 10. The destination telephone number may, e.g., be entered using a touch screen interface, numbered buttons or voice recognition.

In number analysis step 42, the processor 12 analyzes the received destination telephone number to decide whether the phone call should be made via GSM directly or via a connection set up by the connection server 21. The analysis may comprise separating the country code from the remaining part of the destination telephone number. By comparing the country code of the destination telephone number to the country code of the telephone number associated with the GSM handset, it is determined whether an international call is to be made. For example, when calling from a Dutch GSM handset 10 (telephone number e.g. +31 612345678) to a German destination telephone 31, 32 (e.g. +49 123546789), the processor 12 will know from the country code of the destination telephone number (+49) that the connection should be established via the connection server 21. Optionally, the connection server 21 is only used for calling to a specific set of countries. A list of countries for which the connection server 21 should or should not set up the telephone call may be stored on the storage means 15 of the GSM handset 10.

The processor 12 of the GSM handset 10 may also be able to recognize destination telephone numbers associated with specific telecommunication providers that the user does not want to call via the GSM network directly, e.g., because said provider charges high costs for setting up a call. Usually, specific ranges of telephone numbers are assigned to specific providers. Such information may be stored on the storage medium 15 of the GSM handset 10 and the processor 12 may recognize such a number and decide to set up the call via the connection server 21.

It is to be noted that the GSM handset 10 may even make it possible to use the connection server 21 for setting up a call with a destination telephone, not having a telephone number. For example, an IP number, Skype username, MSN username or other type of unique personal identification code may be sent to the connection server 21. If the connection server recognizes the person that has to be called, the connection server 21 may set up a VoIP connection to the Skype application, MSN application or other VoIP applications of the person to be contacted. If in the number analyses step 42 it is determined that the destination telephone number should be called via the GSM network directly, a normal GSM phone call is established in GSM connection step 46. If the connection server 21 is to be used, e.g. because the destination telephone is in a different country, the processor 12 controls the GSM transceiver 13 of the GSM handset 10 to call the connection server 21. The GSM handset 10 may, in server calling step 43, contact the connection server 21 by calling a fixed telephone number or a random number within a predetermined range of telephone numbers. For a fast and reliable connection, the processor 12 may be programmed to use a unique connection server telephone number assigned to the user or GSM handset 10. In that way, there will almost always be a connection line available when calling the connection server 21. Alternatively, multiple users may share one connection server telephone number and the connection server may forward the call to an available connection line. In a further alternative implementation, the GSM handset 10 tries another telephone number from the predetermined range of telephone numbers when a first attempt of contacting the connection server 21 fails due to, e.g., a busy connection line.

When being in contact with the connection server 21, in data transmission step 44, the GSM transceiver 13 of the GSM handset 10 sends the destination telephone number to the connection server 21. The destination telephone number may, e.g., be sent using DTMF signals or a separate SMS message. In addition to the destination telephone number, a user identification code and/or security code may be sent to the connection server 21 to allow the connection server 21 to check whether the user and/or the GSM handset 10 are authorized to use the connection services provided by the connection server 21. The user identification code and/or security code may be sent to the connection server 21 automatically or the connection server may request the user to enter such codes before setting up any connection with the destination phone.

The connection server 21 uses the destination telephone number to set up a VoIP connection to the destination phone 31, 32. In call establishing step 45, the GSM handset 10 uses the VoIP connection set up by the connection server 21 to establish the call with the destination telephone 31, 32. The user of the GSM handset 10 can now have a conversation with the user of the destination telephone 31, 32 until one of the users disconnects. The flow diagram in figure 5 shows the steps taken by the processor 24 in the connection server 21. In data receiving step 51, the GSM transceiver 23 in the connection server 21 receives the destination telephone number and a user identification code from the GSM handset 10. The user identification code may be specific for the GSM handset 10, for the user of the GSM handset 10 or for a combination of both. For example, the telephone number associated with the GSM handset 10 may be used as identification code. A disadvantage of using telephone number of the GSM handset 10 is that it may easily be forged. It may therefore be advantageous to use a non public user specific code for identifying the user. Optionally, the connection server asks the user to enter a PIN code before proceeding with making any connection.

In authorization step 52, the processor analyzes the incoming data to determine whether the user is known and authorized to use the connection services, whether the user has sufficient credits for making any calls, whether it is possible to set up a connection to the received destination telephone number, whether the user is authorized to use the service to call this destination telephone 31, 32 and many other things.

If the user is not authorized to make the requested call, in rejection step 55, the connection server 21 may simply break the connection to the GSM handset 10.

Alternatively, a prerecorded message may be played for informing the user about the rejection. Optionally, the call may be forwarded to, e.g., a help desk.

If the user is authorized to make the requested call, in connection step 53, the connection server 21 controls the VoIP module 25 to set up a VoIP connection to the destination telephone 31, 32. If the destination telephone 31, 32 is in another country, the VoIP module 25 may also use a second connection server 22 in said other country for setting up this VoIP connection. If the destination telephone 31 , 32 is not an IP phone, the connection server 21 must be able to call a telephone on the GSM/PSTN network.

When the connection server 21 has set up the connection to the destination telephone 31, 32, the user of the GSM handset 10 can have a conversation with the user of the destination telephone 31, 32 via the connection server 21 or multiple connection servers 21, 22.

It will be appreciated that the invention also extends to computer programs, particularly computer programs on or in a carrier, adapted for putting the invention into practice. The program may be in the form of source code, object code, a code intermediate source and object code such as partially compiled form, or in any other form suitable for use in the implementation of the method according to the invention. It will also be appreciated that such a program may have many different architectural designs. For example, a program code implementing the functionality of the method or system according to the invention may be subdivided into one or more subroutines. Many different ways to distribute the functionality among these subroutines will be apparent to the skilled person. The subroutines may be stored together in one executable file to form a self-contained program. Such an executable file may comprise computer executable instructions, for example processor instructions and/or interpreter instructions (e.g. Java interpreter instructions). Alternatively, one or more or all of the subroutines may be stored in at least one external library file and linked with a main program either statically or dynamically, e.g. at run-time. The main program contains at least one call to at least one of the subroutines. Also, the subroutines may comprise function calls to each other. An embodiment relating to a computer program product comprises computer executable instructions corresponding to each of the processing steps of at least one of the methods set forth. These instructions may be subdivided into subroutines and/or be stored in one or more files that may be linked statically or dynamically. Another embodiment relating to a computer program product comprises computer executable instructions corresponding to each of the means of at least one of the systems and/or products set forth. These instructions may be subdivided into subroutines and/or be stored in one or more files that may be linked statically or dynamically.

The carrier of a computer program may be any entity or device capable of carrying the program. For example, the carrier may include a storage medium, such as a ROM, for example a CD ROM or a semiconductor ROM, or a magnetic recording medium, for example a floppy disc or hard disk. Further the carrier may be a

transmissible carrier such as an electrical or optical signal, which may be conveyed via electrical or optical cable or by radio or other means. When the program is embodied in such a signal, the carrier may be constituted by such cable or other device or means. Alternatively, the carrier may be an integrated circuit in which the program is embedded, the integrated circuit being adapted for performing, or for use in the performance of, the relevant method.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb "comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

CLAIMS:

1. A GSM handset (10) having a telephone number with a country code corresponding to a first country, the GSM handset (10) comprising:

a user interface (11) for receiving, from a user, a telephone number of a destination telephone (31 , 32) having a telephone number with a country code corresponding to a second country,

a GSM transceiver (13) for communicating with other GSM transceivers using the GSM standard,

a processor (12) coupled to the user interface (11) and the GSM transceiver (13) and being arranged to analyze the received telephone number to determine whether the second country differs from the first country, and if it is determined that the second country differs from the first country:

control the GSM transceiver (13) to call a connection server in the first country,

- control the GSM transceiver (13) to send the telephone number of the destination telephone to the connection server (21),

control the GSM transceiver (13) to employ a VoIP connection between the connection server (21) and the destination telephone (31, 32) to establish a telephone call between the GSM handset (10) and the destination telephone (31, 32).

2. A GSM handset (10) according to claim 1, wherein the processor (12) is arranged to control the GSM transceiver (13) to send the telephone number of the destination telephone (31, 32) to the connection server using DTMF signals or an SMS text message.

3. A GSM handset (10) according to claim 1, wherein the processor (12) is further arranged to control the GSM transceiver (13) to send a user identification code and/or security code to the connection server (21).

4. A GSM handset (10) according to claim 1, wherein the processor (12) is further arranged analyze the received telephone number to determine whether the received telephone number is associated with a provider from a predetermined list of providers and if it is determined that the received telephone number is associated with the provider from the predetermined list of providers:

control the GSM transceiver (13) to call a connection server (21) in the first country,

control the GSM transceiver (13) to send the telephone number of the destination telephone (31, 32) to the connection server (21),

- control the GSM transceiver (13) to employ a VoIP connection between the connection server (21) and the destination telephone (31, 32) to establish a telephone call between the GSM handset (10) and the destination telephone (31, 32).

5. A connection server (21) for establishing a telephone call between a GSM handset (10) having a telephone number with a country code corresponding to a first country and a destination telephone (31, 32) having a telephone number with a country code corresponding to a second country, the connection server (21) comprising:

a GSM transceiver (23) for communicating with other GSM transceivers using the GSM standard and for receiving, from the GSM handset (10), the telephone number of the destination telephone (31 , 32) and a user identification code identifying the user of the GSM handset (10),

a VoIP module (25) for establishing a VoIP connection between the connection server (21) and the destination telephone (31, 32),

a processor (24) coupled to the GSM transceiver (23) and the VoIP module (25) and being arranged to analyze the received user identification code to determine whether the user is authorized to use the connection server (21) for establishing the telephone call, and if it is determined that the user is authorized to use the connection server (21) for establishing the telephone call:

control the VoIP module (25) to establish the VoIP connection, and - employ the VoIP connection and the GSM transceiver (23) to establish the telephone call between the GSM handset (10) and the destination telephone (31, 32).

6. A telecommunication system comprising the GSM handset (10) according to claim 1 and the connection server (21) according to claim 5

7. A method for establishing a telephone call between a GSM handset (10) having a telephone number with a country code corresponding to a first country and a destination telephone (31, 32) having a telephone number with a country code corresponding to a second country, the method comprising the GSM handset (10) performing the steps of:

receiving (41), from a user, a telephone number of the destination telephone (31, 32),

analyzing (42) the received telephone number to determine whether the second country differs from the first country, and if it is determined that the second country differs from the first country:

via GSM, calling (43) a connection server (21) in the first country, - via GSM, sending (44) the telephone number of the destination telephone (31, 32) to the connection server (21),

via GSM, employing (45) a VoIP connection between the connection server (21) and the destination telephone (31, 32) to establish a telephone call between the GSM handset (10) and the destination telephone (31, 32).

8. A method for establishing a telephone call between a GSM handset (10) having a telephone number with a country code corresponding to a first country and a destination telephone (31, 32) having a telephone number with a country code corresponding to a second country, the method comprising a connection server (21) performing the steps of:

receiving (51) from the GSM handset (10) the telephone number of the destination telephone (31, 32) and a user identification code identifying the user of the GSM handset (10),

analyzing (52) the received user identification code to determine whether the user is authorized to use the connection server for establishing the telephone call, and if it is determined that the user is authorized to use the connection server (21) for establishing the telephone call:

establishing (53) a VoIP connection to the destination telephone (31, 32), and

employing (54) the VoIP connection to establish the telephone call between the GSM handset (10) and the destination telephone (31, 32).

9. A computer program product for establishing a telephone call between a

GSM handset (10) having a telephone number with a country code corresponding to a first country and a destination telephone (31 , 32) having a telephone number with a country code corresponding to a second country, which program is operative to cause a processor to perform the method as claimed in claim 7 or 8.