Some users may have experienced issues after upgrading noted Truphone earlier this month. The company has now issued a Truphone update for anyone holding of updating or who have already updated and are experiencing problems.

"The issues Truphone experienced with the new Apple OS 3.1 firmware have now been solved with the release of Truphone for the iPhone version 3.0.3, released today," Truphone notes in an email.

"Apologies once again if you experienced any issues with Truphone over the last week."

Truphone is a mobile Voice over Internet Protocol (VoIP) application that routes calls across the Internet. Calls are free to other Truphone users, those with Skype and Google Talk via Wi-Fi, while calls to destinations worldwide are offered at competitive prices insists the company.

The application, which works with both and , is free and available from the Apple iTunes App Store.