AT commands and SMS don´t work

I have the same trouble in 2 different units of Supreme Fastrack 10. Suddenly, when I write ATI only appers “56000” and with AT&V answers a lot of characters and +FCLASS=0, etc., and at the end S000:000 …until S077=90, no appears ICF, ECHO, IFG

It doesn´t answer to AT+CMGR most of AT commands.

Please help me.

You are no longer speaking to a Fastrack!

I think you’ve accidentally switched COM ports, and are now talking to a Motorola PSTN modem…

No, not Motorola - I meant to say US Robotics!

This is what I get from my laptop’s internal modem:

Look familiar…?

If you try some other ATIx values, you may get some more clues; eg,