Via Talk is a reasonably good, inexpensive, and reliable VOIP service with a huge feature set.
Their one weakness is that their CODEC(s) do not seem to be very reliable for digital transmission of any type so TiVo's daily call is, at best, problematical. There are many settings that can be tried but the reliability, for me at least, was never high and I gave up and switched to PPP over serial for my TiVo calls.
As others have said, if you have a series 2, you can use a USB Ethernet adapter and get your updates over the internet directly.
With a series 1 you have a few options:
1: A turbonet card which allows a wired connection to the internet through your router.
2: An Airnet card which is like the turbonet but connects wirelessly.
3: PPP over serial. This requires a computer nearby running XP or Win 2000 (Vista "might" work) with an internet connection. (PPP works on a series 2 as well)
PPP is what I use for two of my TiVos while I have a turbonet card in my other.
I currently have Via Talk for my phone service but that is all I use it for. I will be dropping Via Talk soon as I have discovered that Skype, with Skype out and Skype in will serve all my home phone needs for about 1/3 of the cost.
OldDog: Places to go, things to do, people to sniff.