An IP phone system requires packet-switched Voice over IP (VoIP), or Internet telephony to transmit telephone calls through internet. IP telephone systems comprise a VoIP private branch exchange i.e. IP PBX and desktop VoIP phones (IP Phones) which are connected to a VoIP service provider via a Local Area Network (LAN).
PSTN phones and IP phone Singapore are not compatible but you can adapt a PSTN phone to the internet with an analog telephone adapter. With IP phones Singapore, using Internet, calls travel as packets of data on shared lines, avoiding the tolls of the PSTN. The packets travel like any other type of data, like e-mail, over public Internet and/or private Internet Protocol (IP) network to provide a better quality of calls.