We have an Avaya IP system and a Sonicwall PRO 2040 in place in our main office, and it depends on how seamless you want to make things, initially we tried running 2 VLAN's with our DHCP server providing the relevant options to punt the phones into the correct VLAN, the Sonicwall doesn't allow the addition of options into the DHCP service so we ended up running DHCP on a different server.... in the end we set the phones up to have the VLAN configured and the rest of the services it picks up from the IP Office... (So DHCP is back on the Sonicwall for the data users)
...still at the moment we can't get our VPN to work, the DHCP server on the IP box gives an IP address to the remote user and so the user ends up on the wrong VLAN, this problem I'm still looking to solve...
(oh and SCN is a total PITA)
Regards
Dave