Fax passthrough – H323 IOS gateway to ATA H323

Posted: May 28, 2006 by cciestudy in Fax

** Please do not edit this blog due to table formatting issues **

Fax passthrough redundancy

Gateways will send each packet twice. Is useful if the network conditions are bad with packet loss and errors. Eradu packets send madithini.

ATA          Gateway         Results

Enabled     Enabled           Success

Enabled     Disabled          Success

Disabled    Enabled           Failure

Disabled    Disabled          Success

RTP Payload types

NTE and NSE are used to define a system of transporting tones and other telephony events over RTP, similar to DTMF relay

NTE                                         NSE

Named Telephony Event             Named Services Event

IETF – RFC 2833                       Cisco proprietary

RTP Payload 101                       RTP payload 100

Payload types for Fax upspeedThis is the payload type that tells the remote gateway to upspeed the codec to g711 for the fax call.

Default on ATA: 126/127 for fax upspeed to G.711m-law/G.711A-law

Default on Router: 0 for G711ulaw, 8 for G711alaw

You can change this in dial-peers

dial-peer voice 1500 voip

rtp payload-type cisco-pcm-switch-over-ulaw 126

rtp payload-type cisco-pcm-switch-over-alaw 127

ATA Settings


Connect mode: 0x90000480 (Bit 7 – 0/1 Disable/enable)

RTP Payload for upspeed to match IOS setting

Connect mode: 0x90000404 (Bit 2 – 0 means 126/127, 1 means 0/8)

  1. I wish Cisco could get their WAAS solution right and finally beat up on Riverbed.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s