Method for the routing of communications to a voice over internet protocol terminal in a mobile communication system

A system comprising at least a mobile station, a first call control node, a second call control node, a directory and a home location register, the system further comprising:

• a mobility entity in said first call control node configured to receive a registration message from said mobile station, said registration message comprising a logical name referring to said mobile station, to request a mapping of said logical name to an International Mobile Subscriber Identity referring to said mobile station from said directory, and to request updating of a location of said mobile station from said home location register by specifying said International Mobile Subscriber Identity;
• a call control entity in said second call control node configured to receive a call set-up request message, said call set-up request message comprising at least a called party number, to send an inquiry message from said second call control node to said home location register, said inquiry message comprising at least said called party number, to receive an inquiry response message from said home location register comprising at least a roaming number, and to send a call set-up request message to said first call control node;
• and
• a call control entity in said first call control node configured to request a mapping of said called party number to said logical name referring to said mobile station from said directory.

A computer program embodied within a computer readable medium, the computer program being configured to perform the steps of:

• receiving a registration message from a mobile station, said registration message comprising a logical name referring to said mobile station;
• requesting a mapping of said logical name to an International Mobile Subscriber Identity referring to said mobile station from a directory;
• requesting an update of a location of said mobile station from a home location register, said request comprising said International Mobile Subscriber Identity;
• receiving a call set-up request message, said call set-up request message comprising at least a called party number;
• sending an inquiry message to said home location register, said inquiry message comprising at least said called party number;
• receiving an inquiry response message from said home location register comprising at least a roaming number;
• sending a call set-up request message to another call control node;
• and
• requesting a mapping of said called party number to said logical name referring to said mobile station from said directory.