Does anyone know of a UK retailer who sells the breakout adapter for connecting 2 analogue phones to a 2830Vn or 2860Vac? UK, so BT style required.
I've picked up a couple of routers second hand and they've missing the adapter. My searching so far has failed to find an equivalent
Thanks.

Same question here. In the absence of a specific part a DSL microfilter will serve as a 1 line adapter, as it contains the capacitor to make the phone ring. Otherwise I'm thinking I could get a twin-master box and improvise.

The person I bought the routers from found the VOIP adapter for me in the end, so I didn't need to DIY it.
It does look like 2 normal master sockets on the end of an RJ11 cable should be able to do the trick - it is only 2 capacitors and the connectors. I'd bought the bits to do it, but then got the official one.

FWIW does it have any kind of part number or ID on it?

None whatsoever