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


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…