Protip: if you are connecting older #telephones (1980s/1990s) with #BritishTelecom plug to #VOIP via an #ATA (either standalone or that built into your router), beware that many RJ11 to BT socket adaptors now lack the ringing capacitor for the bell wire - some #telephone sets won't ring without it!

If you have a spare #ADSL filter this contains the capacitor and can be used to get your #phone to ring (plug it into BT socket from the ATA and telephone into the BT socket on the filter)