The 4P4C connector is the standard modular connector used on both ends of telephone handset cords, and is therefore often called a handset connector.
This handset connector is not a registered jack, because it was not intended to connect directly to the telephone lines. However it is often referred to as RJ9, RJ10, or RJ22.
The connector has arrived but with the cables connected, I don't get the dial tone, I get a faint fizzle sound so either the connector's faulty or the pins are not the same in each socket!
Got an RJ10/11/45 crimper tool and a packet of RJ10 plugs. Got a spare curly cable, cut an end off and crimped a new RJ10 plug on (same wire arrangement as the other end due to reverse polarity of connector) and now have a long enough telephone hand set cable.
Its handy having a crimper tool for future repair jobs!