What kind of reliability and quality is available with VoIP? In particular with using Comcast as a service provider.
At my job we have many employees that work from home. that being said we provide IP phones for their use. Regardless of cable, fios, dsl, etc.; I have found that a minimum bandwidth of 768k will provide you with nice results for any connection. Adding some QOS to the router helps as well. anything below that speed has always given my users a lot of jitter.