The reason fring has people [talking](http://www.smithonvoip.com/voip-product-reviews/fring-iphone-review/) is that it is the first application to offer mobile VoIP across different platforms. fring is described as: a mobile internet service and community that allows users to access and interact with a variety of communication services such as Skype, MSN Messenger, Google Talk, ICQ, Twitter, Yahoo!, AIM and any open SIP based VoIP service provider. So in contrast to [truphone](http://www.truphone.com/) (which also has a client for the iphone and a handful of other mobile devices) this is a software client that allows you to make free mobile calls from your phone through any of the approved services as mentioned above.

We use Skype here at Chromis in addition to our SwitchvoxSIP server. So after a very easy installation and registering with fring, I plugged in both my Skype ID and SIP account settings (which are normally reserved for my counterpath eyebeam softphone). Both services registered immediately and I was able to place a test call to my colleague Brian via Skype. Aside from some tolerable echo, this went off without a hitch. We then did a SIP call from my fring extension to his Polycom IP550. Also no issues there. Call quality was great. We then initiated a SIP to SIP iphone conversation via fring on via our iphones. Again a little noticeable echo but definitely tolerable. My only complaint was the heat my iphone was generating after a 10 minute call. It doesn’t get this hot on a cellular call unless I’m on for over 30-40 minutes.

I then tried a SIP to PSTN call to my neighbors house, who, in order to thwart solicitors, requires you to enter your telephone number if the caller ID information is unknown. I found that I could not complete the call as I did not have a keypad to enter the number to punch through. So fring may want to take a look at a way to get the DTMF tones once a call is placed. I called back about 10 minutes later and the call went through. I’m still not sure what the how I was able to get through. So I told him the reason I was calling and he said that it wasn’t bad call quality, but a little off. He said it “sounded like I was calling from Berlin, like it was an international call”. He noted that he could understand everything that I was saying.

This is what happens when you try to make a call over the 3G network.

fring claims to be compatible with 3G, WiFi, GPRS, or Edge networks. According to Steve Jobs, AT&T has a policy banning VoIP over their 3G network . The picture above shows what happens when you try to make a call using the 3G Network. The error message in the photo reads: “Voice is not available with 3G connection type.” So unlimited internet does not always mean “unlimited”. At least apple iphone users get free wifi at Starbucks.

fring is a great application that has its little quirks, I probably won’t use it all the time, but if you see me in Starbucks drinking coffee while talking on the phone, it might not be the cellular network I’m talking on…

Click here to download fring for free on your iphone or ipod touch.