Question : Bandwidth Requirements for VOIP and Data

Is there a basic formula for required bandwidth vs. number of PCs/VOIP Lines?  Specifically, would a T1 be sufficient for supplying data and voice services to a branch office with say 5 computers and 5 telephones?  The network traffic is minimal, and would consist of limited Internet and terminal client sessions.  I've done some Googling, but haven't been able to come up with any definitive answers for this.  I also understand that everything's relative - I'm just trying to get a ballpark approximation.  Anyone with experience or an opinion is welcome to give their 2 cents worth.  Thanks in advance.

Answer : Bandwidth Requirements for VOIP and Data

VoIP call bandwidth is calculated based on the type of codec you specify.  If you use G.729, which most people do on WAN links, you should assume that each call will use about 30k of bandwidth.  It's realistic that all 5 phones being used simultaneously on G.729 would use about 150-200k of bandwidth...leaving 1.3Mbps for data...it's ajudgement call on the data requirements, but it sounds like a T1 would be plenty.  Carefule with the codecs...G.711 is a Cisco default and uses more bandwidth, like 80kbps/call...it's all about the codec.