CNET News.com

Some broadband customers who use the Internet for phone conversations are complaining that their incoming calls are being blocked.

The problem, which surfaced about two weeks ago, apparently prevents some Net phone users who are also broadband customers of Adelphia Communications, Citizens Communications' Frontier and various rural cable providers from receiving calls, according to sources familiar with the situation.

A handful of AT&T's CallVantage Net phone subscribers are among those affected. "We are seeing, sporadically, some instances of blocking by some cable company networks," AT&T spokesman Gary Morgenstern said.