Visibility for devices in the field is extremely crucial. It think the biggest problem for deployed devices is to identify which parts of the connectivity the device is failing at -- for example, after device has booted up, has it authenticated with the network (SIM authentication), Then tools are needed to identify if the device has completed GSM & GPRS registration.
This can be tested by sending an SMS to the device after some time. If device responds via SMS, then GSM registration is confirmed. HOwever this does eat up SMS's in a specific rate plan & can tend be pricey based on # of checks the back end application would need to do with the device.Whether a device has done GPRS registration is only verifiable if the device creates a PDP context, however if the device has the wrong APN and the GPRS network does not allow any open APN to connect, then we cannot identify whether the device has wrong APN or if it just cannot do GPRS registration.This is a good summary & tip covering the breakdown of how a device would need to connect & what troubleshooting tips are to be reviewed.