What displays when you run UAVcast? What is in your drone config file.
I can help easily if you can use Sprint. My set up is with Sprint using Netgear 341U Aircards I bought off ebay. These USB modems have UNIX drivers available. I used UQMI initially, but the UNIX drivers have eliminated the need for it (they connect, plug and play)
Best yet, Sprint offers Static IP addresses for $3 per month. Luckily, Sprint's download speed is increasing and is good enough now (but still not as good as Verizon).