Requirement is to provide an interface to add instruction sets onto existing 3G Modem chipset interfacing with the existing chipset instruction set. The code involves Linux kernel base of approx 100MB and additional approx 50MB to be loaded onto the chipset. The modem choice can be made by the contractor based on experience and availability of SDK.
I developed apps that use 3g modems on arm platforms before. I would love to help you updating into your 3g modem firmware. I have long experience with C.