Event that causes modem to stop searching for new operator

I’m wondering if anyone can explain the inner workings of a registration event sequence. Specifically I’m interested in what causes the device to go from CREG: 0,2 (not registered, currently searching for new operator) to CREG: 0,0 (not registered, not currently searching for a new operator)

For ex I am working with a new provider who’s SIM is supposed to be roaming capable on Rogers. The SIM roams fine on AT&T, but in Canada the device is unable to register on Rogers (probably due to some provisioning error with Rogers). Upon start-up the device will read +CREG: 0,2 for the first minute or so and then give up and go to +CREG: 0,0. What triggers this? Is it a registration timeout? Did the device attempt all visible operators and come to the end of its list? Or maybe there was some interaction with Rogers which ended with a failed registration?

The issue is between Rogers and my provider, but I’m hoping someone can shed some insight on what process the device is actually running through

Thanks

Do you get a +CREG: 3 (Registration Denied) at any point…?

Hi awneil

Haven’t captured a CREG: 3 event, even with unsolicited responses activated. Looks like it simply starts with CREG: 2 and then defaults to CREG: 0 after a minute or two. I have noticed that after some time while the device is sitting on CREG: 0 I will get a WIND: 7 unsolicited response indicating the network is available for an emergency call. When this happens the device reverts back to CREG: 2 as if saying “oh something happened, let’s try registering again…”

I am seeing the network clearly on the 1900 mhz band, as indicated with at+cops? response of +COPS: 0,2,302720

It seems odd to me that the modem would ever default to the CREG: 0 state on its own… why would you ever want the device to not be searching new a new operator if it isn’t already on one? If you specifically don’t want it registered you can turn off the GSM stack with at+cfun=4. That fact that device will do this automatically seems frightening to me…