The brother-in-law is getting ISDN...

oscarBravo

...over Fixed Wireless, which poses one small problem: it won't give him an analogue port to plug his phone into.

The normal solution is to get a TA like the Eicon Diva ISDN Modem, which has two analogue phone ports and a serial port for PC connectivity - that's' what I have, and it's dandy.

Problem is, he has a Mac and it don't have a serial port. Any recommendations for a USB TA that will also provide at least one analogue phone port?

Gavin

if it's just for the phone, why not just get an isdn phone ?

Gav

oscarBravo

It's not just for the phone, hence the need for a USB TA for the Mac. The FWA ISDN box only has one ISDN port, so if you plug an ISDN phone into it, there's nowhere to plug a TA in.

shabbyroad

if interested I've got a USB TA that is Mac compatible....I've no further need for it as I got a router and stuff a while back. PM me if you're interested. it doesn't have an analogue port though...

or you could get a USB->serial adaptor. I think I've got one I no longer need. PM me if interested.

Tenshot

An ISDN S-bus (i.e. the socket you plug your TA or ISDN phone into) can support multiple devices with a simple passive splitter. (For longer lengths, you need to make sure it is properly terminated, but shouldn't be a problem for standard 3m telephone cables).

For the voice side, you could get a stand-alone adapter to provide analogue ports. See for example http://www.vtx.co.uk/remote/anatel200.htm

oscarBravo

Tenshot, thanks for the info. You don't happen to know where I'd get a passive splitter?

I'm waiting for a quote for the Voice Adapter. It'll be interesting to see how it compares to a TA - I located an appropriate unit, the Eicon Diva 852, but it's not all that cheap.

towbar

We use a 3COM ISDN pro ta - External adaptor has usb and analog ports - not sure what cost was.

oscarBravo

Originally posted by oscarBravo
I'm waiting for a quote for the Voice Adapter. It'll be interesting to see how it compares to a TA - I located an appropriate unit, the Eicon Diva 852, but it's not all that cheap.

It started to look cheap when the quote came in: €196+delivery. Looks like it'll be the Diva after all.

iano

Just curious - who is providing ISDN over FWA and where?

Thanks,
Ian.

oscarBravo

Eircom, just outside Ballina, Co Mayo.

There's a bit of a saga to the story that I've documented over the last while on the IrelandOffline boards.

In summary, I have been trying for about 2 years to get ISDN, without success. Earlier this year, I was pointed to Eircom's FWA license, which stipulates that they must provide basic rate ISDN. Since I already had a FWA PSTN line, I asked them to upgrade it. When they said they couldn't, I pointed out that their licence said they had to. Long story short, they upgraded me.

Since then, at least three of my neighbours have also applied for FWA ISDN lines, and have passed their site surveys, so they should be upgraded shortly.

Tenshot

Originally posted by oscarBravo
You don't happen to know where I'd get a passive splitter?

A normal RJ11 splitter should work okay, as long as it's got four pins wired up rather than just the centre two. Preferably one of the ones on the end of a cable, rather than just a big blob of plastic with a plug on one side and two sockets on the other side -- those tend to wobble a bit in the socket and lead to unreliable connections.

(You may find your ISDN equipment has an RJ45 socket instead of RJ11. A standard 4-wire RJ11 cable should still work okay as long as the device has its own power supply and isn't expecting power from the line.)

If you want something a bit more professional, Blackbox in the UK have a splitter that might do the job. Best check with a sales guy first though - if it breaks each pair out separately, then it's no use to you. Search their catalogue for "rj-45 splitter" (with the dash) to find it.

oscarBravo

Actually, I happen to have an RJ45 double socket, a bunch of CAT5 cable, some RJ45 plugs and a crimper: could I make something up myself? Is it really as simple as wiring up all four pairs from the plug to both sockets?

If it's that simple, I've a potential use for it myself. I've an Eicon Diva TA, which gives me my two analogue lines, and my Debian router uses the serial port on it like a modem. I also have a PCI TA which I'd rather be using, but only having one ISDN port I didn't think I could plug both in.

You reckon I could wire up a simple splitter, and plug both devices into it? Use the Diva as an D/A convertor, and the PCI card for comms?

Tenshot

Yep, that should work fine -- strip enough from one end of the CAT5 cable so that you can punch it into the first socket's punchdown block (without cutting it) and then run it on to the second socket as well. Do this for all four pairs (may as well).

Crimp an RJ45 connector onto the other end of the cable and you're all set.

(If you're feeling lazy, you can get away with just doing the centre two pairs. Also remember to make sure the twisted pairs are on the right pins: 4+5 and 3+6, rather than 3+4 and 5+6.)

oscarBravo

OK - that emphatically didn't work.

Rather than the double socket, I decided to wire it through my 48-port patch panel. I crimped a plug onto one end of a length of Cat5, and punched down the pairs at the other end onto ports 45 and 46. I plugged the Diva into one, and checked: D-channel and Link lights on. Plugged it into the other: lights on.

I plugged the Diva into one and the PCI TA into the other: no dialtone. Plugged out the TA: dialtone. Holding the phone off-hook, I plugged the TA back in: crackle crackle pop silence: D-channel and Link are now off!

I plugged the TA out, reset the Diva, and after a while (long enough for a heart attack to be imminent), the lights came back on and I got dialtone again.

I wonder if this is a limitation of the Airspan kit that Eircom are using? Maybe it's a non-standard S-bus, or something. Either way, it looks like this solution is a non-starter.

spongebob

maybe the Airspan will not connect to a passive device like a normal TA . Configuration of Airspan not correct ?

M

oscarBravo

If I get brave, I'll try connecting just the PCI TA to rule that out.

As to configuration, who knows? The local guys are decent blokes, but they don't have the training (or the laptops) to look at the config on the Airspan, and I doubt they'll get Jim down from the smoke on a fishing expedition like this.

Watch this space.

Tenshot

Hmm... strange; electrically, it should work fine.

It's possible either the Diva or PCI card is not happy co-existing with other equipment on the S-Bus (I've seen this before). It's also possible there is some weirdness with the wireless solution that only allows one device instead of several devices to co-operate simultaneously. Each device on the S-bus requests and is assigned a TEI, similar to a DHCP address on an IP network; if this is handled locally in the NT box, instead of by the exchange (as is usually the case) it may be limited to just one address.

Best I can suggest is to take the Diva and PCI card to somewhere with a fixed ISDN line installaton and confirm that they do indeed work together elsewhere (standard Eircom ISDN boxes have two S-Bus connectors on the box itself, so it's straightforward to plug two devices in together).

oscarBravo

I'm guessing it's a limitation of the Airspan box. If, as you say, it's normally handled by the exchange, then that's more than likely the problem.

I get the feeling that the Airspan solution was always intended to be data-only. The fact that it has no analogue presentation leans me further toward this view.

Ah well. Maybe I could consider a completely different approach: 2 ISDN cards, and PBX4Linux...