Question : Basic Networking concepts

I have a simple network consisting of an SBS 2003 server, Terminal Server, basis file/print server, a basic switch,  Watchguard x55e, and 30 workstations in the main office.  (192.168.100.0)  The internet connection is Comcast with a 20mb down and 8mb up and a single static IP
All our phones are digital (non IP)

There are 2 satelite offices each with 5 users that come in via terminal services through a internet connection.  (No VPN)  I should mention that only one satelite office is occupied at a time, so only 5 remote users are active at any one time.
Each satelite office has a DSL internet connection from the local phone company 6mb down and 512 up with a single static IP

A Phone Vendor just installed a phone switch (10.0.0.0) that is compatible with VOIP and wants a VPN between the Main office and satelite offices.  The only VOIP equipment inthe main office is the switch that will communicate with the 5 phones in each satelite offices.

A software vendor has just asked for a VPN between the the main office and satelite offices for use with their software.  their requirements are minimal, they said they require about the same amount of bandwidth as Terminal Services.

I have seen this done with a Cisco 1800 series router at each location and switches capible of VLANs.  I cannot admin this complex setup, so Im looking for some advice making this work as simple as possible.  If it were just VOIP or just Data, I could handle it.

Thanks in advance

Answer : Basic Networking concepts

if you have watchguard at the satellite office you could certainly set it up there the same as at the home office. With so few users you could also put phones on 192.168.200.0 network.

Whatever you have at the satellite office will have to route traffic for the 10.0.0.0 network over the vpn tunnel along with the 192.168.100.0 traffic. If you use the same network for phones as for users at the satellite office, no additional routing will have to be set up at the home office site, if you set satellite up on a watchguard dmz interface at satellite office then you will need a routing statement in the home office to direct that new 10.x.x.x network over your vpn tunnel.

I think you are getting close