Sipgate, an established SIP Voice Over IP provider has announced a new software product for the Apple iPhone.

iPhone users will now be able to use a SIP application directly when connected to WiFi hotspots to make free or reduced cost calls over the internet.

This brings the iPhone in line with other WiFi enabled smartphone which have SIP functionality directly available.

Sipgate appear to be offering their free iPhone product via their USA, UK and Austrian websites although, if the software is truly SIP compliant, there shouldn’t be any geographic limitations to its use.

iCall has a closed beta of their system for the iPhone in work.

iCall allows you to route your incoming cellular network calls to your iPhone via VoIP when you are connected to a WiFi hotspot. You can also send and receive VoIP calls over WiFi.

Watch the demonstration video for more information.