Hi, my dad's phone (motorola V3) has just come back from being repaired as the phone would not turn on.
After putting the sim card back in the phone, we are experiencing a problem when calling, the message states:
Call Failed, Unassigned Number.
If anyone could reply with an answer i would be grateful 
I doubt the phone was actually repaired. Most likely, it was replaced with a refurbished unit.
You may need to give your provider a quick jingle. I'm sure they just need to update some info in their system. You should be able to call *611 right from the handset. That will usually always put you through to the provider.
Let us know how it goes. :-)