[Asterisk-Users] UK ISDN PRI Problems

[Linus Surguy]

Hi Chris,

> I have an ISDN PRI supplied by NTL (ex Diamond Cable, Nottingham) which
> is currently working happily with an SDX Index phone system. I have to

I can't see particular problems with your config, but I have a few comments:

[snip]
> I have a Digium E100p card which is configured in zaptel.conf thus;
>
> span=1,0,5,ccs,hdb3,crc4

You do need to ensure you have networking timing otherwise you'll get
frameslips. I don't know if the 'LBO' really has much effect here, so I
would go for

span=1,1,0,ccs,hdb3,crc4

Now, do you now you have CRC4 on the link? If you get this wrong, this will
cause things not to work, and even if they do, you'll get noise on the link.
Try without.

span=1,1,0,ccs,hdb3

>
> The zapata.conf is like this;
>
> [channels]
[snip]

> rxgain=-5%
> txgain=+5%

Whilst I know other people have posted differently, I can't see any
legitmate reason for specifying gain on an end to end digital link. I'd
suggest these should be zero.

> further red alerts. NTL, bless them, came out with a test rig and
> plugged this in the back of my * box and we made a series of test calls
> which all worked fine, although the NTL chap said the attenuation was
> out as there was a lot of buzz on the line. He suggested we set the line

Sounds like pants to me, but what sort of 'buzz' are you talking about?
Remember this is a digital link and not subject to analogue style
interference.

> Many thanks for any help offered :)

My money is on the CRC4 setting. Try that first.

Linus