[cisco-voip] 7912's and roaming

[IT]

Hi,

My company owns a hotel, and we are looking to bring 7912's to replace
our entire Nextel infrastructure. The issue we are encountering is the 2
separate networks (guest rooms, and the conference rooms).  My hotel
technology director wrote this summary:

***************
We are looking at creating (2) networks on property that will envelope
the entire hotel with wireless access. One network will cover the
sleeping rooms and back office areas and one will cover just the
conference rooms. Each network will have a distinct IP range and will be
maintained by a different vendor. Each network will have wired and
wireless access. We are looking to buy Cisco 7920 phones for our
associates. We want to make sure these phones will be able to seamlessly
roam between the two wireless networks. The AP's on both networks will
most likely be Cisco 1200's. 
 
Could we effectively accomplish the routing these phones needs if both
networks had a Cisco 3750 switch as their core. Most likely the Cisco
Call Manager will be directly linked off the Sleeping room core switch.
***************

Our VOIP consultant has told them that a 3750 core could not handle
this, and they would need to move to the 6000s. I am responsible for
keeping this project in budget, and changing the infrastructure is going
to make my life hell. How have people done this in the past?

Thanks,
Avidan