Siemens Mux_guide_v06 manual Virtual channels and AT commands

Multiplexer User's Guide

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2.2 Virtual channels and AT commands

Please note that a cellular engine designed for multiplex operation does not include three different devices. Only one single air interface (RF part) is available.

As mentioned before the multiplexer enables one serial interface to run three sessions simultaneously. All incoming or outgoing calls are connected to the device.

Channel 1 supports the full range of functions, which is available without multiplexer tool. Channel 2 and 3 are connected to a different AT interpreter and support a subset of the functional range of channel 1, for more details refer to Table 1.

Table 1: Comparison of multiplexer channels
	Voice calls	Data / fax calls	SMS	GPRS	Phonebook	AT
	incoming	incoming	incoming	connection	management	commands
	outgoing	outgoing	outgoing
Channel 1	!	!	!	!2)	!	!
Channel 2, 3	!	-	!	!2)	!	!1)

!indicates that the functionality is available on the channel

---indicates that the functionality is not available on the channel

1)

2)

except for AT commands related to data and fax calls

only two channels can be used parallel to transmit GPRS data

Examples

•While a data call is in progress on channel 1, you can send a short message on channel 2 and edit the phonebook on channel 3.

•When receiving a fax on channel 1, you are able to check the battery capacity using the appropriate AT command on channel 2 or 3.

Note

Due to the technical requirements of multiplexer mode, data and fax calls can only be set up on logical channel 1 while GPRS connections can be established on every channel. Several AT commands have a different behavior on channels 2 and 3. Additional information regarding restrictions and interferences between the channels can be found in chapter 3.1 and in [2].

Mux_guide_v06 Page 10 of 36 30.06.2004