I love when companies give Walt Mossberg something to test, and like it even more when Walt tries extra hard to make something easy to understand like he did today.
Basically in his review of the T-Mobile @ HOME service he points out the warts of the system, especially the Home Alarm system and Fax machine issues. The Home Alarm issue can likely be solved by Next Alarm, as their Alarm Broadband Network is the ideal compliment to an IP based phone system. The faxing issue is one that has been a hassle for most people in VoIP also and while there are solutions, what I'm finding easier these days is to scan and email to send a fax, and to have one of those free services to receive faxes by email.
The best and most revealing line about the @HOME service though is this one:
This new system is not a so-called voice-over-Internet-protocol phone system, such as Vonage. It doesn't carry your phone calls wholly over the Internet, but merely uses the Internet to get them to the T-Mobile cellphone network, which then carries the calls as if they had been made on a cellphone.
What Walt's referring to is UMA and how T-Mobile uses ATM to transmit data from one point to another. Its not IP end to end, but does use the 'Net from his house to the ATM backbone. I'm glad he said that because it differs from other services already out there which do use SIP and IP end to end like Earthlink's TrueVoice, BroadVoice and mostly CallVantage, though some users are on MGCP.