3GPP TS

Release 1998483GPP TS 07.10 V7.2.0 (2002-03)Annex A (informative):Advice to TE software implementersThe multiplexing protocol allows a number of virtual channels to be established between a TE and an MT. The TE isnormally responsible for establishing and clearing down each virtual channel, although the MT may autonomously clearthe entire multiplexing session.Each channel will start life as an instance of GSM 07.07, and will allow the normal AT command procedures for bothGSM 07.07 and GSM 07.05. Any changes made to the AT register settings will be valid within the virtual channel only.If registers are saved to non-volatile memory then the changes will apply to the defaults for the AT registers and willaffect new channels from that point on. Such changes will only affect other active channels if they are reset with ATZ.Changes to the phonebook or to SMS messages will, of course, be on a global basis.The software in the TE sitting above the multiplexing protocol is recommended to establish a virtual channel and leaveit “idle” for the reception of incoming calls according to responses as defined in GSM 07.07. When an incoming callarrives the software may then cause an appropriate application to become active in order to receive the incoming call.The previously “idle” channel will then be occupied with this call and so the TE software is recommended to establishan additional channel to take over from the previously-idle channel in preparation for other incoming calls orindications.Because the ISO HDLC transparency mechanism must be used if it is supported by the MS, the TE shall always try toconfigure the multiplexer with this transparency mechanism. If it is not supported by the MS, the TE shall configure themultiplexer in the basic option.3GPP