SIP is an emerging VoIP technology which we believe will dominate digital telephony in many markets.
We have evaluated several approaches to SIP telephony:
Analog phone based: We tested Vonage DigitalVoice—a low-cost phone service based on analog-to-SIP technology—for more than a year, and reported on it in Vonage DigitalVoice Broadband VoIP Service (BBHR 2/23/2003);
Digital phone based: We used a pair of snom 100 Ethernet-based VoIP phones from snom technology AG, based in Berlin -- one at our house and the other at our daughter's house in California; and
PC based: We used Windows Messenger, which provides SIP telephony for Windows XP, with a Eutectics IPP 200 USB handset and the Free World Dialup service from pulver.com.
To connect between our in-home network and our cable modem, we used a "SIP-aware" Intertex IX66 Internet Gate firewall, made in Sweden. The snom phone at our daughter's house was connected to her DSL modem through a pair of Phonex Neverwire 14 HomePlug powerline Ethernet bridges and a cable/DSL router.