About three quarters of global service providers plan to offer voice-over-IP services via an IP Multimedia Subsystem (IMS) infrastructure by next spring, according to a new report from Infonetics Research.

While IMS has been forwarded as an enabler of multimedia services, Infonetics’s research found – and Telephony’s reporting on IMS echoes – that carriers are deploying IMS gear for less exotic applications, like next-generation voice services.

IMS deployments can be expensive and complex, so service providers have been reluctant to commit to rip-and-replace network upgrades. The alternative is to find a service that can justify – and benefit from – new IMS equipment. Surprisingly, consumer VoIP services, and not multimedia applications, have made the most sense cost-wise.

Deploying IMS for VoIP today also lets carriers leverage that gear for more advanced services later. “As service providers accelerate their transition to VoIP to more efficiently compete, and as more of them experiment with new mobile and multimedia services, IMS will be the glue that bridges their heterogeneous networks together and assures standardization of those services," Infonetics analyst Stéphane Téral said in a statement.

Yet even as they look to a future in which IMS enables more services, service providers had strong interoperability concerns. More than half of the respondents tabbed worries about interop between different types of next-generation voice and IMS equipment as a “strong barrier” to deploying IMS in their networks today.