Abstract: For implementing an emergency call system between a telecommunication device and an emergency call center, the telecommunication device includes a log-in and log-out state via a switchable log-in function at a VoIP telecommunication service provider via an IP infrastructure consisting of at least one router. The emergency call center has a public IP number via which, in the log-out state of the telecommunication device, an emergency call connection diverting to the VoIP telecommunication service provider is safeguarded between the telecommunication device and the emergency call center.

Abstract: For implementing an emergency call system between a telecommunication device and an emergency call center, the telecommunication device includes a log-in and log-out state via a switchable log-in function at a VoIP telecommunication service provider via an IP infrastructure consisting of at least one router. The emergency call center has a public IP number via which, in the log-out state of the telecommunication device, an emergency call connection diverting to the VoIP telecommunication service provider is safeguarded between the telecommunication device and the emergency call center.

Abstract: Method for operating a voice terminal connected to a remote private automatic branch exchange, communication arrangement, and voice terminal The present invention relates to a method and a communication arrangement for operating a VoIP voice terminal connected to a remote IP private automatic branch exchange, for example Centrex or hosted PBX, with there being a VPN connection between the VoIP voice terminal and the network of the carrier of the remote private automatic branch exchange and with communication between the voice terminal and the remote private automatic branch exchange taking place via said VPN connection. Problems arising during NAT translation when the voice terminal is located in a local network whose IP addresses are not valid in the carrier network are advantageously avoided thereby.