I’ve just spent over a day trying to get this piece of information out of Draytek, so appreciate it!
On the newer Draytek routers with VoIP capabilities (Vigor 2820 and some of the later ones) you no longer connect the handset (or PABX) to a standard RJ11. Instead both analogue lines come out on a single RJ11/RJ12, and you get an adapter so you can plug two standard BT handsets in to it. I assume this only applies to UK models. Anyway, if you’re wiring to a PABX, BT jacks are a complete pain in the rear, so if you want to connect an RJ11 to a twin-pair cable and go directly to a krone block the pin-out is (officially):
- Line 1 – pins 2 and 5 (centre two)
- Line 2 – pins 3 and 4 (one out from centre, or outer on RJ11)
That is to say the middle two pins and the two straddling – and numbering as if it was an RJ12 with six positions, even though the contacts may be missing from an RJ11. Heck, if you don’t know how to number an RJ12 you’re probably better off with the BT jacks.
This is logical and probably most telecoms people’s first guess, but it’s nice not to have to go for trial an error or smash their adapter apart (assuming you can’t connect an AVO into a BT-style socket conveniently).
For what it’s worth, I’ve been using Draytek VoIP kit for about eight years now – some of the best going in the market it serves, and I’ve got rather a lot to compare with. It’s a pity the company is so hard to get hold of for technical support as they won’t answer a general question straddling the product range – only individual serial-numbered units. Therefore I can’t get a list of kit for which this applies – I need to ask them one at a time giving the serial number of an extant unit. I suspect they don’t want too many dumb questions swamping them, but not so brilliant for professional users though – if it’s not in their FAQ you’re left to trial-and-error.