Method for detachment of MS moving between communication systems

A method for detachment of a mobile set moving between communication systems, comprising:

• a) receiving, by a service node of a communication system, a detachment request from the mobile set;
• b) transmitting, by the service node of the communication system, a delete context request message for the mobile set to a first service node of another communication system;
• and
• c) transmitting , by the service node, a detachment indicator to a second service node of the another communication system,
• wherein the service node of the communication system is different from the service node of the another communication,
• wherein both the service node of the communication system and the first service node of the another communication system store context information related to the mobile set, and
• wherein the mobile set moves between the service node of the communication system and the first service node of the another communication system without an area updating.

An apparatus for detachment of a mobile set moving between communication systems by a service node of a communication system, comprising:

• a transmitter for transmitting a detachment request to the mobile set, transmitting a delete context request message for the mobile set to a first service node of another communication system, and transmitting a detachment indicator to a second service node of the another communication system,
• wherein the service node of the communication system is different from the first service node of the another communication system,
• wherein both the service node of the communication system and the first service node of the another communication system store context information related to the mobile set, and
• wherein the mobile set moves between the service node of the communication system and the first service node of the another communication system without an area updating.

An apparatus for detachment of a mobile set moving between communication system by a service node of a communication system, comprising:

• a receiver for receiving a detachment request from the mobile set;
• and
• a transmitter for transmitting, by the service node, a delete context request message for the mobile set to a first service node of another communication system, and transmitting a detachment indicator to a second service node of the another communication system,
• wherein the service node of the communication system is different from the first service node of the another communication system,
• wherein both the service node of the communication system and the first service node of the another communication system store context information related to the mobile set, and
• wherein the mobile set moves between the service node of the communication system and the first service node of the another communication system without an area updating.