Municipal wireless LAN mesh startup Tropos Networks is expanding its work with Hewlett-Packard Co. (NYSE: HPQ) and has quietly added $15 million of VC funding to its coffers as it eyes the grand prize of Philadelphia.

HP is working with the startup to provide the towns of Franklin, Tenn., and St. Cloud, Fla., with municipal wireless systems for city workers and public broadband access. HP will supply the wireless devices while Tropos is handling the mesh infrastructure.

Tropos is also in the catbird seat for the Philadelphia citywide WiFi project. The firm is the mesh supplier for both of the two finalists: EarthLink Inc. and HP.

Bert Williams, VP of marketing at Tropos doesn't have that much to say on the subject, at least not yet. "What I can say is that we are on both the Earthlink and HP teams. Beyond that I can't comment," the marketing man tells Unstrung.

Deployments of the wireless network in Philadelphia are expected to start sometime in October.

In the face of this potential expansion, Tropos has been building up its venture capital funds. The firm has quietly added $15 million to its pile over the last six months. Tropos has so far announced that it has received $13.5 million in three rounds of funding, plus an undisclosed amount from Intel Capital (see Tropos Taps Intel).

Investors in the new $13.5 million "inside round" include current investors such as Benchmark Capital and Duff Ackerman & Goodrich LLC (DAG), according to a source that Unstrung spoke with.

Tropos isn't saying anything about the new moneys. "We haven't announced anything about additional funding yet," says Williams.

But, when pushed on the matter, he didn't deny that the firm has recieved additional cash.

And Unstrung hears that the firm may announce more "strategic" money coming in soon.

— Dan Jones, Site Editor, Unstrung