Nokia phones with “Internet Call” feature are very useful gadgets.eg:E71,E51,E66,N80,N95… They provide very reliable internet connection thru WLAN. Often there are complaints regarding the 3G/GPRS connection, the main being the difficulty in using “Internet Call” thru 3G.
The users wonder, “it works thru WLAN, they it should work thru 3G”. ie they assume the settings are 100% correct. But not always this is true. Especially in the case of SIP settings, most providers dont really need the proxy settings to get things work. The Internet Telephone wizard provided in Nokia phones use Gizmo as the provider, and this particular provider perhaps need the proxy settings. So when the users “copy-paste” the settings , they use the proxy settings too,
Try removing the proxy settings from the SIP settings for these providers and you’ll never need third party software like Fring and Nimbuzz for SIP calls. These are good programs in their own, but when we have a native capability, why should we bother others’ servers ?