By default, the 7940G is delivered with Skinny Protocol SCCP and therefore only works in Cisco call server environments. However, SIP firmware can be installed which makes the phone usable on the fritzbox , among other things. You can find numerous instructions for this on the internet. However, this procedure and subsequent integration is only recommended for experienced users. Cisco Systems is the world's leading provider of networking solutions for the Internet. The product range for data, voice and video communication extends from multiprotocol routers, workgroup systems, ATM and Ethernet switches to dial-up access servers and software routers and corresponding network management software. Cisco delivers end-to-end solutions for all areas of internetworking: LAN, campus, WAN and r.
eBay