Thanks for the tip. We have been staging many hundred of our point-of-sale devices with active SIM's in the devices mainly for initial testing in the factory.
We then move the SIM's to a basic keep-alive rate plan so the devices can traverse through our distribution channel. We used to spot check our devices at one every 15 devices, to reduce the cost of activating sim's for testing, however very quickly we found that testing every device further reduced DoA devices & allowed us to fine tune our inventory as devices were registered once they tested.
Key item here is negotiating a really good keep-alive rate plan with the carrier or to ensure some tools carriers allow for a testing phase with their m2m SIM's.