I think this is more common than you think. When runnung a breadcrumb application, it is common for the MC75 to loose telephone connectivity and forward the data when the connection to the cell network is re-established. Your challenge would be to have a suitable data store for the inmformation you collect --- possibly an upload when the device is in a WI-FI coverage area... The assisted GPS is dependent on cell communication, but the native  GPS works independently

Mike,          Absolutely, the GPS functions autonomously, that is to say, no assistance from an external source required.  You can however, utilize an external service to pre-load almanac information which simply enables the device to render a quicker initial lock on the satellites ("time to fix" ) or during "fade out" periods.  This is an IP based serivce (in our case SUPL) which can be accessed via the carrier IP network, or via WiFi, to the public internet. I hope this helps.