I have been using Siemens Gigaset A580IP for couple of months now. I find it works well with Nonoh.net, Voipbuster.com and Asterisks based system. Here is my brief review.

  • Excellent voice quality.
  • has both VOIP and land line option.
  • Connects to multiple VOIP service providers (upto 6).
  • Can easily switch VOIP provider.
  • Can connect to corporate VOIP system based on Asterisks or other open standard based solution
  • In expensive
  • Runs Linux inside 🙂

What I don’t like:

  • Setup take time initially, primarily because its slow to respond. But once its setup it works beautifully.
  • You can’t dial another VOIP service provider directly, for example you can’t dial anyone on username@serviceprovider, you can only dial numbers. How ever you can receive calls if someone calls your username@gigaset.net
  • Cant connect to Skype, primarily because Skype uses a propriety protocol.
  • Not a replacement for Skype video as it doesn’t do video.