Call routing in a telecommunication system

A telecommunication system for routing calls, the system comprising:

• a mobile communication system comprising at least one mobile services switching center and at least one base station connected thereto, and mobile stations arranged to establish a telecommunication connection to the mobile services switching center through the base station by using a first predetermined telecommunication protocol on a radio connection,
• a packet data network, external to said mobile communication system, wherein data to be transmitted is arranged to be transmitted in data packets according to a protocol specified for the packet data network, the packet data network protocol being other than the first predetermined telecommunication protocol,
• a server configured to communicate with the mobile services switching center and said packet data network, said server being configured to arrange messages according to the first predetermined telecommunication protocol supplied from the mobile services switching centre as such into data packets according to said packet data network protocol to be forwarded through said packet data network, the server being further configured to decompress messages according to the first predetermined telecommunication protocol arranged as such in the data packets according to said packet data network protocol and supplied from the packet data network to be forwarded to the mobile switching center, and
• at least one terminal of a second wireless communication system, other than said mobile communication system, arranged to establish a telecommunication connection to said mobile communication system through the packet data network and the server to the mobile switching center, said terminal being other than a mobile station of the mobile communication system, wherein
• said terminal is arranged to establish a first part of the telecommunication connection to said packet data network by using a second predetermined telecommunication protocol, other than said packet data network protocol and said first predetermined telecommunication connection, through which first part the data packets according to said packet data network protocol are configured to be transmitted,
• said terminal is arranged to transmit and receive in said data packets the messages according to the first predetermined telecommunication protocol arranged as such into the data packets according to said packet data network protocol, and
• the terminal of said second wireless telecommunication system is arranged to emulate a mobile station of said mobile communication system.

A terminal configured to establish a telecommunication connection to a mobile communication system through a packet data network of a first communication system and a server instead of a direct connection to the mobile communication system, the telecommunication connection comprising a first part between the terminal and the packet data network for transmitting and, receiving data in data packets, and a second part between the packet data network and the mobile communication system, the terminal comprising:

• a transceiver configured to use a packet data network protocol of the first communication system to receive and transmit data in data packets over the packet data network on the first part of the connection;
• and
• an emulator configured to emulate a mobile station of the mobile communication system by transmitting and receiving in said data in data packets messages according to a first predetermined telecommunication protocol of the mobile communication system, the first predetermined telecommunication protocol being other than said packet data network protocol and used in the mobile communication system to receive and transmit data, wherein the terminal is further configured:
• to perform call control signaling through said packet data network to said server,
• to decompress speech frames and signaling messages according to said first predetermined telecommunication protocol in data packets according to said protocol specified for the packet data network,
• to decrypt encryption in the received frames according to the first predetermined telecommunication protocol, to encrypt the frames to be transmitted according to the first predetermined telecommunication protocol,
• to block de-interleave and unmix the decrypted frames, to block interleave and mix the frames to be transmitted, and
• to encode and decode channel and speech coding.