Truphone who provide a SIP standard voice over IP calling system for mobile handsets of the Symbian S60 platform as well as some iPods and the iPhone have announced that they will now support Paypal payments for customers using iPods and iPhones.

While a number of debit and credit cards were already accepted, customers will now be able to use Paypal through their device to add land-line calling credit without the need to resort to using a web-browser equipped personal computer.

At the GSMA World Congress in Barcelona, Nokia announced that it would be partnering with Skype to provide Voice over IP functionality on future handsets starting with the forthcoming Nokia N97 smartphone.

Rather than running Skype as a seperate application for Symbian, Nokia will be integrating Skype with the built-in address book to allow simple and direct calling/answering of Skype contacts.

The Nokia N97 handset provides both 3G and 802.11b/g WiFi connectivity so owners should be able to use Skype wherever they are.

Skype is a proprietary peer-to-peer VoIP protocol and as such can only communicate with other Skpe devices. There is no word yet as to whether the Nokia N97 or other future Nokia handsets will be supporting any open VoIP protocols such as SIP which would allow for greater interoperability.

Blonde 2.0 for Mashables.com brings us news that mobile p2p VoIP provider fring has released it’s API for third party developers.

This will enable others to develop new applications and add-ons for the fring platform.

The fring platform supports mobile devices such as the Symbian Series 60, Sony Ericsson UIQ, Windows Mobile 5 & 6 and the iPhone.

As a network, fring also integrates with Skype, AIM, Twitter, Google Talk and the industry standard SIP protocol.

Picked up on Surya Andreas’ blog, we have an article detailing his trials and tribulations with testing out potential Voice over IP client candidates for his Symbian/UIQ based mobile phone.

Fring, Nimbuzz, Truphone and Gizmo are mentioned along with Skype and I-Skoot. He seems to hold Fring in the best regard at the moment for it’s general all-round abilities.