Slashgear brings news that there is now a VoIP app in the Apple App Store for the iPhone (and iPod Touch) which allows IP calling over 3G networks.

The software, known as iCall allows for incoming call notification even when the application is not running.

This signals a lifting of the 3G VoIP calling restrictions which Apple imposed on iPhone apps.

Skype has made a deal with Verizon Wireless which will see the peer-to-peer Voice over IP service made available over Verizon’s 3G and WiFi networks for mobile devices.

The deal will allow free* Skype-to-Skype calling over the Verizon network.

As The Inquirer points out, major mobile telecom network providers have been reluctant to embrace VoIP communications due to the effective change in business model which it could herald. The deal which is to be offered to US Verizon Wireless customers is seen as being a big push to take marketshare from AT&T who are only providing Skype for their iPhone customers.

*free meaning the call itself between the Skype clients, obviously the network costs remain.

Startup operation iSkoot is aiming to offer a Skype VoIP solution which will work over mobile telephone networks.

One of the main problems with Skype (other than it’s incompatability with SIP) is that it utilises client bandwidth to route call data in a Peer-To-Peer (P2P) network model. Obviously, when you’re on the end of a contended and potentially quite low-bandwidth / high-cost GPRS or 3G mobile link, you don’t really want that.

iSkoots concept seems to revolve around the concept of having telcos install iSkoot hardware at their gateways to make the connection to Skype. The call is completed between the handset and the iSkoot hardware at the gateway using the normal GSM network so presumably 3G is not required although a ’smartphone’ is probably necessary to run the iSkoot software.

This system allows the mobile user to place and receive calls on the Skype network without incurring massive data charges and the telcos continue to make money on the calls at the normal rate – perhaps even better for the telcos as they don’t have to pay other network connection costs.