Charter Communications is expanding voice service offerings from Charter Business to include SIP trunking. SIP trunking is intended to deliver voice service to large and mid-size businesses through a converged voice and data fiber network."Charter Business SIP Trunking will enable customers with an IP-PBX to take maximum advantage of their IP capabilities by converging data and voice over the same access connection," said Jim McGann, SVP of Charter Business, in a statement.