GPRS Shield v1 - SIM900 does not find the network


I have the v1 GPRS shield, with an AT&T gophone sim in it, but when I power things up according to the wiki at viewtopic.php?f=24&t=2135&p=7790&hilit=sim900+does+not+find+network#p7790 .

Oddly, when powering up, I only get odd characters when powering up, nothing like "RDY

+CFUN: 1


+PACSP: 0".

To answer the questions on the page, for the AT commands given,
AT+CSQ gives +CSQ: 14,0
AT+CREG? gives +CREG: 0,0
AT+CGREG? gives +CGREG: 0,0
AT+COPS? gives +COPS: 0

Also, poking around a bit, AT+CBAND? gives +CBAND: GSM850_MODE,ALL_BAND, and looking at AT+CBAND=?, that gives +CBAND: GSM850_MODE,ALL_BAND, which isn’t listed in either the 1.00 or 1.03 AT spec linked on the wiki page. Trying to set this to allow PCS_MODE results in ERROR.

I’m not really certain what to do at this point. Trying to list the available carriers with AT+COPS=? takes a minute to return just '+COPS: ’ and then seems to freeze, even after waiting 10 minutes. I’d love any pointers, etc, just something to get this working.


Ok, as a minor update (didn’t want anyone to waste time if not needed), I got a T-Mobile SIM. Things seem to have improved, as I got the following:


+CSQ: 17,0


+CREG: 0,1


+CGREG: 0,1


+COPS: 0,0,“T-Mobile”


I’ll do more work tomorrow and post any further questions, but preliminary findings suggest AT&T isn’t friendly with this device.

As a quick update, I’ve been able to connect and do HTTP stuff, send texts, and voice calls with the T-Mobile SIM. The AT&T SIM worked great in their handset but was a dud in the shield, the T-Mobile SIM works great. I’m thinking AT&T is doing some sort of device filtering on their system, but I don’t care enough to delve that deep into it.

Hi aseelye, thanks to your feedback! :smiley: