Voip the ericsson dialog 4425 ip vision system phone is on of the highest specification ericsson ip telephones in the dialog range it is designed to work on any ip ready ericsson telephone system if was connected to a standard telephone line or a different type of extension it would not work the ip system phones like the ericsson dialog 4425 need to be allocated an ip address on the network for them to function high specification system telephone as the ericsson dialog 442