Larry,
Why do it the hard way?? Get your netvision phone re-configured with Skinny protocol and it the appears to the call manager as an SP12+, much easier than trying to use a gateway and you get the added benefits of Call Manager features (pick-up, names etc.).
The gateway method sucks, do it the better way. If you got the phone direct from Symbol and they knew you were connecting them to CM then the rep wants shooting (US people this is an expression and not an instruction). If you've had them a while then they may pass on a small charge for the new protocol on the phone.
Paul