Injunction-happy VoIP co Truphone today "welcomed" Apple's launch of the SDK for the iPhone.

Apple boss Steve Jobs revealed that although VoIP apps would be approved for the iPhone if they worked over Wi-Fi, GSM-based solutions would be banned from the official App Store.

Truphone says its engineering department will be examining the SDK to see how it can help with the development of a Wi-Fi Truphone client for the iPhone.

"We've already had a number of enquiries since the SDK was announced, because we were the first company to publicly demonstrate VoIP on the iPhone", said James Tagg, Truphone's CEO.

"And our response today is that, clearly, we'll be studying the SDK and investigating the obvious opportunities it brings."