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.

Slashdot has a current discussion about which domestic router is best for Quality of Service (QOS) provision for Voice over IP.

The original question posed is by someone using a Linksys WRT54G wireless broadband router with Bittorrent and other high-bandwidth applications to consider. Unfortunately, the WRT54G isn’t quite cutting it when used alongside Vonage.

Inevitably for Slashdot, there is some gravitation toward open-source products. Open firmware for the WRT54G is suggested by some while another comment mentions that m0n0wall, an open-source firewall VPN distribution, can be deployed on relatively low-end commodity hardware and provides the type of QoS required.

Jaxtr is another new VoIP based service this time offering VoIP from your website; be that a blog, Myspace, Orkut etc.

The Jaxtr service appears to involve adding a widget to your website which then allows your website visitor to call you directly, send you a voicemail using VoIP or send an SMS to your mobile phone.

Jaxtr also offer reduced-cost distance/international calling services.

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.

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.