this depends on how you communicant and connect to the head office
i am assuming you will be using a L2 vlan over the data-link connection you have
if you are gonna using one ip range over one vlan you can use one flat vlan for both data and voice this is simple but not best practice
if you can use two differnt vlans one for voip and one for data this option better and then you do the intervlan routing in the 3550 where the ip phones and voice gateway can be place in the voice vlan and PCs in the data vlans
also you need to consider DHCP if its gonna be from a local device/server or from the head office !!
I know the basics for Cisco routers and switches but what I want to know is, if I set up VTP on a switch, is there a way to send it through routers to other switches? This will probably end up more hassle than gain, but it's interesting and cool to p...