Now playing: When Net calls met cellular

Internet telephony software specialist SIPquest said Monday it and wireless network equipment maker Nortel Networks are adding Internet-telephony capabilities to Research In Motion's BlackBerry, Sony Ericsson's P900 and other smart phones. The Net-phone user interface will come from Ottawa-based SIPquest, and Nortel's MCS 5200, which is network operator equipment for video conferencing, online collaboration and other advanced telephone services.

The pairing is further evidence of the collision course of cell phones and voice over Internet Protocol (VoIP), which is software that lets a broadband connection also act as a phone line. VoIP has already replaced about a million traditional wireline home phones, and is growing at a rate of about 7 million new home lines a year, according to some analysts. For cell phone operators, VoIP is a likely add-on to wireless broadband services, another avenue of attack the Bell operators stranglehold on the home phone market.