Method for detecting the reachability of a terminal in a communication network

A detection device for detecting reachability of a terminal previously served by a first access device of a registration area of a communication network, wherein the first access device is unable to manage sleep and waking periods of said terminal, then served by a second device of said registration area, wherein the second device is able to manage said periods, the detection device comprising:

• a transmitter;
• a processor;
• and
• a non-transitory computer-readable medium comprising instructions stored thereon which when executed by the processor configure the detection device, which has not been informed of a change of access device and gets information indicating that the terminal is being served by the first access device, to:
• exchange messages with the terminal for registration and negotiation of the sleep and waking periods of the terminal,
• obtain an item of information relating to data to be transmitted to the terminal, and
• use the transmitter to send a contact-establishment request message to said terminal during a determined waking period of said terminal.

A system for detecting the reachability of a terminal previously served by a first access device of a registration area of a communication network, wherein the first access device is unable to manage sleep and waking periods of said terminal, then served by a second device of said registration area, wherein the second device is able to manage said periods, the system comprising:

• a detection device comprising:
• a transmitter;
• a processor;
• and
• a non-transitory computer-readable medium comprising instructions stored thereon which when executed by the processor configure the detection device, which has not been informed of a change of access device and gets information indicating that the terminal is being served by the first access device, to:
• exchange messages with the terminal for registration and negotiation of the sleep and waking periods of the terminal,
• obtain an item of information relating to data to be transmitted to the terminal, and
• use the transmitter to send a contact-establishment request message to said terminal during a determined waking period of said terminal;
• at least the first and second access devices;
• and
• the terminal, which is able to receive the contact-establishment request message during one of the terminal's waking periods.