So after much research into this issue I just would like some confirmation that I am well and truly stuck for now on 4.2.8. Here's my story and if anyone can offer a solution it would be greatly appreciated.

I'm a fledgling IOS developer and as such wanted to maintain IOS 4.x compatibility for the game I'm working on so I had ignored updating my iPhone to anything newer till now. I decided that it was time to drop IOS 4.x support and move to supporting 5.x and higher.

I fired up Cydia on my iPhone and found to my disappointment that I had no valid 6.x blobs. I now only have 4.2.8, 4.2.10, 5.0.1, and 6.1.3 available for this iPhone. Well, I could live with 5.0.1. I then proceeded to create a custom firmware for 5.0.1 which thanks to some great tutorials installed without issue. I thought I was in the clear. I proceeded to setup Cydia and all my tweaks, restored my apps, provisioning profile, and so on. Then I got a text message from a friend asking why I hadn't answered any of his calls all day !#?

This is when I discovered that my iPhone which by now is at 5.0.1 for IOS and a non-updated 1.0.05 modem firmware. At the time I didn't understand the ramifications of this baseband mismatch. After much searching the consensus seems to be this:

1. With Verizon CDMA the Baseband is tied to the IOS version
2. Just like IOS signing the window for updating a Baseband is tied to the life of the IOS version it was designed for
3. No method currently exists for getting a working Baseband that is no longer being signed.
4. Symptoms of a mismatched IOS/Baseband. iPhone will continually cycle from searching to carrier name, incoming or outgoing calls will not work, messaging and WiFi will work.

In closing if any of the above is incorrect or you have a solution, please correct me and I'll update the post to reflect that change. I hope this post can save some other people a lot of research.