Feature request implement VOIP to usable level not only push notification iPhone

On the iPhone VOIP apps can only signalize an incoming phone call by push notification. And then the user has to accept the notification, enter the code, accept the notification a second time and accept the phone call.... impossible to really use it!

On Android smart phones (e.g. HTC) VOIP over the SIP protocol is implemented into the system so that the user does not see any differnce between common phone calls and phone calls over SIP. The phone rings the same way, idependent wheather a common phone call is comming in or a VOIP phone call.

This is a hugh advantage and very handy, the same time it is a hugh disadvantage and leak of feature for the iPhone.

Please implement VOIP over the common protocols into the system or implement an API for VOIP apps so that they can signalize an incoming phone call by normal ringing.

That would make VOIP really usable on the iPhone and bring it to the same level like the competitors with Android phones.

But please make not an Apple-service out of it. First of all there are enough VOIP providers present, secondly Apple cannot take all country specific things into account, and third please do not make a closed Apple-only system out of an existing open system.