The iPhone has been around awhile, so it isn’t too of the oridnary to realize that there are also some great voip apps available for the iPhone to make voip calls and make better use of the expensive phone bill you pay monthly just to have an iPhone.

TruPhone for the iPhone
Now if you ever wanted to make low price calls from GSM without voip, TruPhone has you covered.  They offer low-priced international calls via the GSM network.  The best feature is if you dial an international number, the iPhone app does not use iPhone’s data network but the call is redirected to a Truphone access number in your country.

Get it direct from the app store: via iTunes

Fring for the iPhone
Even more popular for making voip calls through the iPhone is the fring software.  This allows you to call regular phones using either SkypeOut or SIP over Wi-Fi. Fring also includes an all in one IM for Skype, Google, ICQ, MSN, Twitter, AIM, and Yahoo contacts.
Get it direct from the app store: via iTunes

We expect more apps to come, but with Apple’s close watch it can be hard for more developers to get their own software running on the iPhone.