Motorola V3 Unassigned Number Message

Hi,

I'm wondering if anyone can help. I turned on the V3 and have just
tried to make a call from my phone (which has been working well no
issues) except that when I try to dial out it Displays Unassigned
Number message. There's credit on the phone and I have tired other
sim's in it but the phone displays that message. I've done a couple
of resets but nothing seems to work

Thanks in advance for any help

Jamie