When money’s tight, you turn to those you know for help. That’s the path telecommunications software developer Trinity Convergence is following to land $3.1 million in second-round venture financing.

Intersouth Partners of Durham and Core Capital Partners of Washington, D.C., led the round and were joined by Mid-Atlantic Venture Funds of Reston, Va. All three were involved in Trinity’s initial $1.5 million funding last summer.

Trinity officials couldn’t be reached for comment.

The company creates packet voice and fax software for telecommunications equipment suppliers to facilitate Internet telephone services and help users sidestep heavy long-distance rates. New York-based market research firm Frost & Sullivan estimates the packet telephony market will grow from $5.4 billion this year to $36 billion by 2005.

Trinity’s management team came over from Blue Wave Systems after that company was acquired by Motorola’s computer group. The company uses a Motorola platform for its flagship software product, VeriCall.

Although Trinity’s Raleigh headquarters is in a telecom hub, the company’s main research and development center is in Cambridge, England.