How to send fax/data via Huawei E3131 (aka 420 D) 3G modem?

Question

Huawei

I have a Huawei E173 modem. Data is perfectly sent through it (in the dial-up mode of a point-to-point connection) and faxes, provided that it has previously been switched to the “2G network only” mode by the AT ^ SYSCFG command with the corresponding numbers.

I bought a more modern Huawei E3131 (aka Huawei 420 D) from MTS (sold under the umbrella brand "modem with data transfer rates up to 21.6 Mbps"). So, this new modem, when trying to make a data call, displays NO CARRIER. I tried to send a fax - the fax program also writes "error". Does he fundamentally not support these types of calls? Or do I need to enable and disable something additionally? There is no such modem on the Huawei website at all :(

On AT+GCAP, the modem responds with +GCAP: +CGSM,+DS,+ES - what do all these abbreviations even mean? I found on some site that DS is data compression, ES is error management. The corresponding AT commands that control all this were also given there - but the modem swears at them with ERROR. But what CGSM is is not clear, I just hoped that Circuit-Switched GSM, which, together with DS, could mean the ability to transmit data.

Old 173 answered +GCAP: +CGSM,+FCLASS,+DS.
+FCLASS is about faxes, but I don’t really need faxes, I’m primarily interested in data in point-to-point mode.

Answer 1

Did you change the SIM card? Check the service through the "cabinet".
It was also such that data transfer did not fundamentally work on 3G. With what it is connected there was no time to understand. I had to force GPRS on the modem. Speed ​​was not important.

Answer 2

Did you have IMEI on the E173 from a modem, tablet or smartphone?
Did you include
AT^SYSCFG=13,1,3fffffff,0,0 or
AT^SYSCFG=13,1,3FFFFFFF,2,4
?