said by tpalik :Check this link out : »
www.telcodata.us/telcodata/telco···ange=549If I recall correctly Comcast needs to have an arrangement with the original owner of the number block to do the port. Other than ATTWS and Broadwing (which is now Level3) I don't know the rest of these guys. They likely would have had porting agreements with AT&T (allowing the original port to CV to take place) but perhaps not Comcast.
You are not limited to those companies. The new carrier needs to have a presence in the