BT DSL Filters

dahamsta

I have two BT sockets in my flat and I need to use them. I thought that if I disconnected the wee RJ11-to-RJ11 connector on an Irish DSL filter and replaced it with a BT to RJ11 connector I'd be OXO, but 'tis not to be. Will I have to buy specific BT DSL filters or am I missing something?

If I have to buy them, any online recommendations?

adam

Redshift

dahamsta wrote:

I have two BT sockets in my flat and I need to use them. I thought that if I disconnected the wee RJ11-to-RJ11 connector on an Irish DSL filter and replaced it with a BT to RJ11 connector I'd be OXO, but 'tis not to be. Will I have to buy specific BT DSL filters or am I missing something?

If I have to buy them, any online recommendations?

adam

Last time I was in PC World they had dsl filters with the the UK style jack on them.

julius

Well you could always get 2 RJ11 sockets and replace the BT ones?!?!?
It would save you a lot of trouble.

dahamsta

Nah, it's part of a plate incorporating TV outlets, not my apartment so I don't want to make any additions.

No PC World in Cork, I guess I could try Maplins but they're out the other side of the bloody city.

adam

bk

dahamsta wrote:

Nah, it's part of a plate incorporating TV outlets, not my apartment so I don't want to make any additions.

No PC World in Cork, I guess I could try Maplins but they're out the other side of the bloody city.

adam

Maplins will have them, time for a trip to the North side for you I think

You can get them online at:
http://www.dsl-warehouse.ie

Hotblack Desiato

Plug the BT-to-RJ11 adapter into the wall and an Irish DSL filter into that?

d-j-k

There's nothing amazingly different about a BT phone socket or DSL wiring.

Just plug a BT-RJ11 adaptor into the socket on the wall. Then plug the Irish DSL microfilter into that.

In the UK, BT use RJ11 connectors for DSL anyway. So, normally a microfilter over there has a BT plug on the end that goes into the wall and 2 sockets 1 X RJ11 for the DSL modem (unfiltered) and a BT socket for the phone.

Btw, you can get nice modular wall plates that you can add any combination of sockets to .. e.g. RJ11, RJ45, + Fconnector + speaker connectors + standard antenna connectors etc etc..

MK Electric do them.. ask in a wholesalers.

dahamsta

Read my post folks: I tried that, it didn't work.

I'm going to collect some BT filters this avvo, I'll fiddle around with them a bit, see what happens.

adam

d-j-k

That's very odd!

There's no reason why it shouldn't work as the phone line's just carried on 2 wires regardless of what plug is used.

Be aware of one thing:

The official way of wiring up an RJ11 plug has the phone line carried on the centre two contacts. (this is how everyone in the world does it)

A BT plug carries the phone line on the outer two pins (the Line 2 positions)

Because RJ11 plugs and BT plugs are usually crimped onto flat telephone cable many British phone cords have the RJ11 plug wired the wrong way... i.e. the phone line is carried on the wrong pins.

The phones / modem / fax then has an RJ11 port with the pins wired to match the weird plug.

Basically it's often easier for a manufacturer to change the internal wiring of the device than cross the cables over in the plug!

The result of this is that some UK products have their RJ11 sockets wired backwards, others have them wired correctly.

If you plug a normal RJ11 - RJ11 cord into many UK phones (particularly BT branded devices) you'll get no dialtone.

Also, if you use a BT to RJ11 cord, it may have the RJ11 wired incorrectly, so the normally wired phone/modem may not get a dialtone!
If you're using a cord that didn't ship with your DSL modem, this is a serious possibility. I'd suggest that you plug a standard eircom phone into the end of the cable and see if you can hear a dial tone.

(this causes regular problems in the UK too!)

There are some other "creative" non-standard uses of the spare pins on RJ11 sockets around so for maximum compatability with an eircom socket you're best to use a cable that only has the centre two terminals connected!

Also there's a rather complicated UK-arrangement for 3rd wire ringing. Basically, normal phones use 2 wires.. these carry the DC signals (for voice) and when your phone rings an AC voltage is applied over the same pair. In Ireland this is 25Hz about 75Volts.

A BT socket has a capacitor and circuitry that sends this AC voltage down a 3rd wire.

This setup prevented the bells of old telephones from tinkling when extension phones dialled using pulse dialling.

Phones in other countries had these capacitors and other circuitry built in to the phone rather than the socket so were uneffected by "tinkle"

Most phones on the UK market are designed for use with normal 2-wire systems too. However, you'll still get the odd phone (again mostly BT branded) that expect 3rd wire ringing voltage and won't ring on a normal 2-wire set up (Such as that found in Ireland or the United states)

Basically, BT wiring's weird and totally non-standard... So don't presume anything's as it should be with RJ11 plugs/sockets used on UK equipment.

---

Make sure you use a proper adaptor, not a BT to RJ11 cord!

dahamsta

d-j-k, I can't test the DSL because it isn't activated yet, but I was testing with an unpowered phone and wasn't getting a dial tone.

Got some BT filters from Ed anyway, working fine now. Thanks Ed.

adam