After updating to ios 6 my phone had to be restored. Now it will not acitvate. I am receiving the message that ther server is unavailable. However, I can not use my phone at all until it is activated. why can I not activate?

Well, 99.9% of the time, the cause of this issue is the fact the phone was jailbroken/hacked to unlock it for use on networks other than the network the phone was originally locked to. Apple maintains a database of officially unlocked iPhones, and when Apple's servers detect phones such as yours, activation stops & you get the message you got.

So, either get a sim card from the carrier your phone was originally locked to, or get it officially unlocked.