Make data-connection
Connect a speaker or a phone to the analog-line to obtain more information about the progress of the connection.(hear the ring and the progress of connection build- up.)
Make call in data-mode (ATD without semicolon).
Control, if it is ringing ("RING" response), ring on phone or speaker.
Control, if call is answered (ring stops, data-sounds can be heard. ISDN: connect- response on terminals.) Eventually, connection disconnects again.
Causes:
a.analog: Normally the setting of the Analog-modem is not important, but is has to be set to autodetect and the fastest protocol. Alternatively it could also be tested with setting exactly the protocol you will use. (Analog- Modems from Altec: use the AT+MS=xxx command. (Specially if you have troubles calling from Analog to GSM.)
b.analog and ISDN: possibly incompatible settings of protocol and speed. If calling to GSM, the GSM should expect a data-call. (Settings AT+CBST=xxx, AT+CSNS=4, AT+FCLASS=0, see above). It is advisable to check with different GSM network-providers and in both calling directions, in our experience this could sometimes solve the problem. For ISDN we had less problems calling from ISDN to GSM. For Analog the direction GSM- >Analog caused fewer problems.
c.ISDN: additionally there comes the influence of the fixed-networks. Normally the public digital network allows data-transmission, but it could be that the local extension of the company-exchange is not activated for data- transmission. (see error-messages at GSM-side)
Remarks for Swiss Customers
There are some differences between the GSM-Network-providers.
- Generally speaking, we had better results connecting to and from ISDN using SIM- Card from Sunrise.
-On the other hand, with Analog-Modem (V.32) you better use Swisscom. With Sunrise we were only able to originate a V32-call, but not to receive one. Nevertheless, Sunrise informed us, that it should be possible.
-Not tests were made with Orange (coming soon).
