Report : 'cm data' doesn't behave like expected while not under coverage


Hello all,

I have made some experiment and I found out that ‘cm data’ was still giving "Connected : yes " when we were not under coverage for + than 1 min. But it answers “no” when we only enter “cm data connect -1”.
Is it normal?


Hi @alex1,

Yes, this can be expected because the cellular connection does not require constant coverage for the data context to be maintained. The modem would automatically disconnect if there were a lack of coverage when a periodic signalling event is required by the cellular network, like a tracking area update in LTE, so eventually it would show disconnected. Prior to that, if you were to bring the modem back into coverage, the data connection should be maintained without requiring any additional signalling. Let me know if this doesn’t help.



Hi @rkirk,

Thanks for your answer, this is not what I expected but I could get connection again after losing coverage and coming back to it, so with same settings it worked at least.
Do you know how much time it should be like this?



@alex1, sorry for the delayed response.

The time for this state will really vary depending on several factors:

  1. Which Radio-access technology you’re using (GSM/UMTS/LTE have slightly different signalling procedures and may be configured with different timers)
  2. Carrier-configured signalling timers - the service provider can pass down timer information that controls the intervals between these signalling events.
  3. When your out-of-service event occurred relative to the next scheduled signalling event. If you lose service with 2 minutes left on the timer, you will disconnect in 2 minutes. You could alternatively lose service 2 minutes after the most recent event and stay connected for a significant amount of time. For example, a typical Location Update period is 60 minutes.

Sorry if this is either too much, or not enough information :slight_smile: Let me know. I was going to run a single sample at my desk, but unfortunately my service provider is so strong here that I stay connected, with data transferring, even without antennas!