Xefiro Phone is an open source Voice Over IP (VOIP) / SIP client for iOS. It is specialized to communicate with the video door phone XN.ViPh, produced by Automa, and it is also compatible with Videx phone devices.
It allows you to make and receive video calls, view the video from the door phone before responding and open the gates during the call.
It is synchronized with your contact and it is compatible with all SIP server.
It is based on Linphone for iOS by Belledonne Communications and the source can be downloaded at:
http://apps.byautoma.com/xefiro-phone/ios.zip