also performs the gprs attach procedure at the time indicated in the triggering sms message steps 206 and 208 the terminal from which the triggering sms message is transmitted may also perform the gprs attach procedure slightly before the time indicated in the message if there is no starting time in the message this terminal may connect to the gprs network after having received the status report it may also connect to the gprs network immediately after having sent the sms message or just before the message is sent especially if no delivery report is returned to the terminal when the terminals have performed the gprs attach procedure successfully each terminal registers with the poc application server by sending steps 210 and 211 the server the session initiation protocol sip register request the server acknowledges the request by sending a sip response with the relevant status code i e 200 ok after the registration terminal a may start the session by sending an invite request according to the sip to the poc application server step 212 the invite request invites the other terminals to participate in the session and it includes a description of the session for example the poc server forwards the invitation to each terminal step 213 each terminal acknowledges the invitation by sending a sip response with the relevant status code i e 200 ok having received the acknowledgments from the invited terminals step 214 the poc application server sends an acknowledgment to terminal a step 215 and the poc session step 216 may start one or more parties may be invited to the session in the same manner since the triggering message may be delivered to several terminals fig3 is a flow chart illustrating one embodiment of the sending.