Maximum distance from ISDN 30 - Switch

muirt · 5 Sep 2014 at 15:51

I have an ISDN30 that is located 61 metres away from the switch and was wondering if the distance could cause problems? We are having bad quality on incoming calls only and wondered if the distance could be the issue. I was told that I would be safe within 100 metres but can not find any indudtry standard ruling on this. Does anyone know the recomended distance limitations and do you know where I can locate the industry standard rule on this?

THANKS

Ploppy2k3 · 5 Sep 2014 at 16:27

According to our telco guru here its 100m as you thought.

muirt · 5 Sep 2014 at 16:46

Thanks! Can you ask him if there is any written guidelines on this? Need it to prove to the client that we are well with in recomended distance.

bremen1874 · 5 Sep 2014 at 18:11

What sort of cable are you using? I thought that although the cable used for ISDN looks like standard network cable it isn't (different impedance?, different pin out?, something like that). The 100m limit usually quoted is what applies to Ethernet, which I don't think the connection from the ISDN30 will be.

muirt · 5 Sep 2014 at 19:03

I'm using Cat5 cable from the ISDN box upto my switch.

Ploppy2k3 · 5 Sep 2014 at 19:05

it is normal cat5/5e/6 cable.

I have asked our chap about documentation and he doesnt have any to hand. all he could suggest was to look up the original spec online somewhere! really! never would have guessed lol

muirt · 5 Sep 2014 at 19:07

Yes, Cat5e. I have searched but cant find anything. thanks

Ploppy2k3 · 5 Sep 2014 at 19:16

a little bit of mooching about on Cisco's site has yielded...

100m on Cat5/5e
200m-600m on low attenuation cable.

its all scattered about hence no links but it is there. search for PRI rather than ISDN30

mejinks · 8 Sep 2014 at 02:18

I dont understand what you are trying to achieve. When you say switch, are you referring to a telephony switch (argent/lucent/panasonic etc) or a data switch going into a pbx?

Im only guessing, but you could be experiencing clock slip (timing is important on ISDN30 circuits) and you could be using the wrong cabling (you may need an ISDN PRi crossover cable instead of ethernet crossover)

However, all this is guesswork unless you can tell us exactly how your network is configured step by step.

Caged · 8 Sep 2014 at 23:24

You also need to explain 'poor quality'.

pepp77 · 9 Sep 2014 at 12:51

Usually an ISDN30 box is connected to a PBX via a standard Cat5e cable. Whilst theoretically this allows upto the standard 100m run it is advisable to keep the ISDN box within 10m of the PBX (this is what we advise all customers) for lowest risk of issues.

Using 110 Ohm Multicore twisted cable you should be okay with runs of upto 300m theoretically.