Cox Communications\u00a0has begun carrying voice traffic over its own IP backbone instead of using facilities leased from other long distance providers.The carrier is about a month into a deployment of IP voice gear that will convert TDM traffic generated by its local phone customers into IP for routing over its OC-48 core network. Cox offers local voice services in 10 cities.Formerly, traffic from Cox's local and long distance customers ran over the long-distance networks of wholesalers AT&T, Wiltel and WorldCom (now named MCI).About 20% of Cox\u2019s long distance voice traffic goes between cities touched by the provider's IP backbone and where it also sells local service, says Jay Rolls, Cox\u2019s vice president of telephone and data engineering. The company realized it could save money by trunking that portion of the long-distance traffic on its own IP network, he says.All traffic entering the backbone is stripped of quality of service markers -- just the voice portion is given priority to keep up the quality of the voice calls. Priority is determined by setting the type of service bit in each packet.Rolls says the IP transition will save Cox millions of dollars, but would not specify the amount. Cox uses Cisco and Juniper routers in its backbone.Cox is also using Nortel Networks' Succession softswitch equipment along with existing Nortel DMS local phone switches to carry out the transition. Cox also uses Nuera media gateways to convert the voice traffic to packets.Eventually, the company plans to extend its IP voice trunking to San Francisco, Chicago, Dallas, Atlanta and New York, cities where its backbone extends for the purpose of peering with other network providers, but where Cox offers no local phone service. However, by using these trunks and teaming up with local carriers in those cities to deliver calls initiated by Cox phone customers, the company can save more, Rolls says.That could increase the amount of customer voice traffic handled by the Cox IP backbone by another 20% to 30%, he says.If other carriers migrate to IP backbones, peering will be more streamlined because the traffic won\u2019t have to be converted from IP to TDM for a hand-off, Rolls says -- it can remain IP.