OK I have followed all the wonderful instructions. Jailbroke my phone, installed Cydia,the iPad modem firmware, I then inserted my SIM chip and low and behold, I was able to get a signal from my provider. I then attempted to make a call to my active iPhone 4 and was not amused when I found out that the only way my iPhone 3G could hear voice from my iPhone 4 is in speaker mode or the headphones are plugged into the 3G. I have done quite a bit of searching on this issue and it seems that folks had a similar issue way back with 1.1.X firmware. Many of them were of the opinion that plugging in the headphones and removing them again several times would fix the issue. This hasn't been the case for me. Any head would be greatly appreciated. 
Jigen271
Jigen271