More enterprises are deploying SIP trunking, but perhaps not as much as the partner sector may have hoped.

“T1 lines are still the most commonly used trunking service today, and while their use is declining, our survey shows that North American businesses are using a combination of services; there isn’t going to be a 100-percent cutover from T1 to SIP,” said Diane Myers, principal analyst for VoIP, UC and IMS at Infonetics Research. Myers wrote a new study on SIP trunking and session border controller strategies among enterprises in North America.

“Companies are using SIP trunking for only a portion of their call capacity,” Myers added.

But that stands to change over the next two years. Respondent companies saying they use SIP trunking will grow from 38 percent this year to 58 percent in 2015, Infonetics said. Meanwhile, the percentage of enterprises using T1s will fall from 71 percent in 2013 to 55 percent in 2015.

“One trend is clear: SIP trunking adoption is growing as businesses seek to improve the reliability and lower the cost of communication services,” said Myers.

Among enterprises not deploying SIP trunking by 2015, most said they are satisfied with their existing voice services; others said their existing service contracts would not be up for renewal.