XT55 AT Command Set - Wireless Data Modules

XT55 AT Command Set11.6 AT+CGDATAsNotes• If the MT is in dedicated mode, write command returns "+CME ERROR: operation temporary not allowed".• It is possible to leave the GPRS data mode and enter the command mode by using the V.250 command +++.By using the command AT+CGDATA again, the data mode is reentered. Which context is used to return todata mode, depends on the supplied parameter .If no is specified, this is equivalent to using the V.250 command ATO, which is usable for GPRS connectionstoo. In this case the first context will be used, which is active and already in data mode since it hasbeen activated (the internal context used for GPRS connection without explicitly specifiying a context identifierhas the highest priority).It is possible to use AT+CGDATA to enter the data mode for a context, which is not yet in data mode since ithas been activated. With ATO this is not possible.11.6.1 Automatic deactivation of PDP context during dial-up PPPWhen using the AT+CGDATA write command or ATD*99# or ATD*98# the MT issues the intermediate resultcode CONNECT and enters V.250ter online data state. In V.250 online data state, first some LCP protocolexchange between MT and TE is performed to set up the PPP link. After successfully establishing the PPP link,the MT performs the PDP context activation procedure if the context is not already activated. As a result, the MTis in a "PDP context activated" state within the PLMN, the PPP link is established on the mobile side and themobile is ready for IP data transfer.If the TE wants to close the LCP link the MT may perform an LCP termination request procedure on PPP level.After this LCP termination procedure the MT deactivates the PDP context automatically and the MT returns toV.250 command mode and issues the final result code NO CARRIER.During the implicit PDP context deactivation procedure after LCP termination the TE may change into V.250command state (e.g. by using +++ or by toggling DTR if AT&D is set to 1) before the result NO CARRIER occurs.In this case the application should not try to deactivate the PDP context by using the commands AT+CGACT orATH. If DTR is configured to disconnect data connections (AT&D2), then the application should not toggle DTRduring the implicit PDP context deactivation and before "NO CARRIER" is received.XT55_ATC_V03.03 Page 261 of 459 9/9/05Confidential / Released