is there any voip app out there that will allow me on the iphone to use an sip address and will allow me to do key presses so i can put in when i get prompts, like "press 1 to continue#

i have a n95 and i use gizmo with it, the n95 gives you the option to either do a internet call or cell call like any normal call.

i remember using fring when i had my iphone, but that wouldnt do dial tone presses or run in the background.

this is one of the only reasons i havent went back to the iphone from the 95 besides the camera.