VoLTE is set to be the biggest driver of IP multimedia subsystems (IMS), although operators have been warned that that product alone will not be enough to justify investment.
A new report from Infonetics found that almost five out of six operators (83 percent) will have deployed VoLTE by 2016, compared to the three percent who have rolled it out today.
While VoLTE is the main driver for IMS deployment, operators are also attracted by the ability to offer converged services through multiple access methods.
Researchers said conversations surrounding NFV were central to the IMS market. A majority of operators said they wanted to run IMS networks through NFV within the next two years.
However, the report warned: "If vendors aren't actively developing products suited for an NFV environment, they will fall short in [requests for proposals]."
Diane Myers, Principal Analyst for VoIP, UC and IMS at Infonetics, commented: "Among carriers participating in our latest IMS study, it's clear that although voice over LTE (VoLTE) is the largest driver for IMS, it also presents new challenges such as a limited set of compatible handsets and a weak business case.
“It'll be tough to justify spending capital on a new network for just voice that represents flat-to-declining revenue, requiring providers to look well beyond running voice over IMS."
According to previous research from Infonetics, there will be more than 50 million users of VoLTE by the end of this year, with the Asia Pacific region predicted to dominate.
However, it warned that independent companies might find it difficult to monetise VoIP services, despite a predicted CAGR increase in sales of 12 percent.