A while back I said I was going to post some info on mobile VOIP phones that use WiFi. I've finally had time to play with this stuff and it's very exciting.

I have this new tutorial: http://www.skifactz.com/wifi/wifi_sip_phone.htm

While this is not a really a hack (or it is in a way because my phone was originally designed for Vonage service) it's still pretty exciting.

In the nutshell, you can use a mobile SIP compliant WiFi phone like Utstarcom F1000G to connect to any open AP and make free calls to other SIP phones. This costs nothing other than about $60 for a used phone. If you pay a few bucks more you can setup an account that allows you to call any landline at very low rates.

I also have played with WiFi Sip Wireless phones and I used www.voipbuster.com for my service. I have to say it works very well in hotels. The trick to get around the spash page it to change you laptop's MAC to match the Sip WiFi phones and agree to the terms of service. Once you do this the sip phone should be able to use the free hotel wifi and you can now make and take calls. Remember to switch your laptop back to it;s own MAC and re-agree to the hotel TOS to get it access too.

Brian