The 'worry-free' approach, called Avaya On Demand, is unusual for an equipment provider and is now more commonly offered by service providers, said George Humphrey, director of the new program, which is being announced at Interop Las Vegas 2006. Lucent Technologies and Nortel Networks offer VOIP services for carriers, who then sell the service to enterprises. But neither offers the service directly to businesses, spokesmen for the two companies said.

Avaya On Demand will start at US$25 per month per user for IP telephony services, including voice mail, and an IP-based voice mail service can be purchased separately for $5 per user per month, Humphrey said. A call center can purchase the service for between $50 and $150 per agent.

One new user of the service for the past three weeks is XM Satellite Radio, in Washington, D.C., which is relying on Avaya instead of a conventional service provider because of past difficulties with service providers, said Tanya Callaway, director of technical operations for XM.

'Telcos do offer a call center service, but they don't know the call center business and they can't move fast enough for me,' said Callaway who has worked with several service providers.

XM officials prefer a service to support the company's call center, which has about 1,600 agents for 10 months of the year -- and 3,000 in November and December when demand is high, Callaway said.