SIPphone, a San Diego-based VoIP provider, secured $6 mil. in venture funding, in a round led by Dawntreader Ventures.

It’s the first round of external funding for SIPphone, which will use the investment to expand SIP-based phone service into “non-PC” devices, like adapters, routers, WiFi handsets, and dual-mode mobile phones, the company said in a statement.

“We want to seamlessly link the Internet and the traditional calling world of landlines and mobile phones, and that’s becoming possible as low-cost SIP-based … become a reality,” said SIPphone CEO Michael Robertson, who expects his company to triple in size over the next year.

SIPphone plans include and support an “open standard auto-provisioning system” known as “plug-n-dial”, the company said.

So far, SIPphone’s “Gizmo Project” has attracted 400,000 registered users.