Connection settings for connection between ISDN and GSM terminal

FAQ #100370

In order to establish a connection between PG5 (PC equipped with an ISDN TA (Terminal Adapter) and the PCD is equipped with a GSM terminal Siemens MC35), the initialisation string of the GSM terminal is to be modified.


Since the ISDN TA is communicating using the bearer service V.110, the GSM terminal is to be configured to use this service, too. This configuration is done by editing the init string of the GSM.
Please note that also the ISDN TA must use the bearer service type V.110! Make sure this is the case (other common bearer service types such as V.120 are not supported by the GSM terminal MC35).

The initialisation string of the GSM terminal is to be configured in the Hardware Settings of the PCD. In the "modem" tab of the HW settings, the init string is to be modified. The command "CBST=71,0,1" is to be introduced into the init string of the GSM terminals.

The init string below sets a GSM terminal MC35 into auto answer mode (S0=2) and configures the terminal to use the bearer service V.110 (+CBST=71,0,1).
After the delimiter (semicolon), the command &W causes the modem to store the just entered configuration into flash. Therefore this configuration stays active until the bearer service is changed again (by the use of the command CBST). The reset string ATZ will not restore the default bearer service! 
The expression "\r" doesn't belong to the init string but serves as "End Of String" for the PCD firmware.

The +CBST command :
The table below shows the supported bearer service types as well as the syntax of the command.
Syntax:                   AT+CBST=<speed>[,<name>[,<ce>]]  

<speed> 0 auto bauding

2400 bps( V.22bis)


4800 bps( V.32)


9600 bps(V.32)


14400 bps (V.34)


2400 bps (V.110)



4800 bps (V.110)



9600 bps (V.110)



14400 bps (V.110)

<name> 0

asynchronous modem

<ce> 1


Transparent mode is not supported.

*) default value
This table is part of the manual for the GSM terminal MC35. For additional information, please refer directly to the manual.


PG5 2.0 / Modem

Last update: 30.05.2015 11:13

First release: 19.05.2005 07:51

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