stubborne

CM 3.0.1 and CM 3.1.1

We've recently completed alot of equipment transition from SCC sEPN's to G650 IP Connect. The G650s, for the most part, support local dialtone and PSTN access via ISDN/PRI trunks.

I'm looking for some help supporting faxing (and modem connectivity) across these IP port networks. We've had issues and complaints of poor service since the transition. All of our IP network regions are configured with the same IP codec. Here's the codec config:

Audio Silence Frames Packet
Codec Suppression Per Pkt Size(ms)
1: G.729 n 2 20
2: G.729A n 2 20
3: G.711MU n 3 30
4:
5:
6:
7:

Media Encryption
1: none
2:
3:

Allow Direct-IP Multimedia? n

Mode Redundancy
FAX relay 0
Modem pass-through 0
TDD/TTY US 3
Clear-channel n 0

The IP port networks utilize TN2602 Med's w/ up to date firmware. Any help or suggestions to fine tune this network would be greatly appreciated. Thanks!

I should say we have a solid QoS implementation and plenty of bandwidth.

__________________
Stu

OctelWarrior

First off you are using G729, this compresses the audio and you will lose some quality. I would recommend that any internal calls or calls between an IP endpoint and a local trunk use an uncompressed protocol, such as G.711. If these faxes are coming in on trunks local to the fax machine, you should be able to use an uncompressed codec, offering the best quality. If you are concerned with LAN bandwidth, you can assign all the IP phones to use G.729, but all other calls (fax/modem) would be G.711. There are a few ways to accomplish this depending on your situation.

Also, on page 3, Fax should be set to Pass-through. I don't remember which Avaya doc says this.

__________________
Peronally I'd rather lose phone access than data.

PBXtech.info

 

oozenoz

Am I reading this wrong or are you using a combination of A-law and mu-law companding...?

__________________
- calvin

stubborne

I had put the Alaw codec in awhile back (testing maybe?) but it's never used as MULAW is listed 1st on all codec set configs. I should remove it...

In response to the 1st poster, I will try passthru on fax but I don't get as much complaints or issues w/ faxing as I do with Modem. With Modem Passthru, it does not matter what codec you have config'd in the 1st page list, it will always use G.711 upon modem detection. I've traced calls and verified it does do that. I think the modem issues I was/am having are on the far-end devices (Cisco CallManager based)...

(edit: A-Law was added in support of codecs on adjunct devices, ie CallManager and others.. just haven't removed it)

__________________
Stu

oozenoz

Companding should not be selected based on the type of device; it should be selected based on where the device is installed. mu-Law is NA standard, A-Law is ITU-T standard which is used just about everywhere else. If you are connecting to the PSTN in the US, you would have to use mu-Law because the two algorithms are not compatible - a connection where A-Law is used on the transmit side and mu-Law when received will result in a highly distorted signal after it is decoded and converted.

Best practice is to use the same companding for all traffic routing over a single interface.

__________________
- calvin