Using Prserv For Diagnosing Fax Problems; Prserv Overview - Cisco ATA 188 Administrator's Manual

Debugging the Cisco ATA 186/188 Fax Services
Table 6-1
Problem
The Cisco ATA is not
configured for fax mode or
fax pass-through mode.
The remote gateway is not
configured for modem/fax
pass-through mode.
Fax relay is not disabled
on the remote gateway.
Fax/modem pass-through
method on the remote
gateway is not compatible
with the Cisco NSE-based
method.
NSE payload types differ
between gateways.

Using prserv for Diagnosing Fax Problems

This section contains the following topics:
•
•

prserv Overview

prserv is a tool that runs on a Microsoft Windows-based PC and serves as a log server that captures
debug information that the Cisco ATA sends to your PC IP address/port. The debug information is saved
into a readable text file.
To enable your Cisco ATA to send debug information, you need to set the NPrintf configuration
parameter to your PC IP address and an available port, as shown in the following procedure:
Cisco ATA 186 and Cisco ATA 188 Analog Telephone Adaptor Administrator's Guide (SCCP)
6-8
Solving Common Fax Problems (continued)
Action
For fax mode, the AudioMode configuration parameter should be set to
0xXXXX0012 (X = value not applicable) for the Phone 1 port of the
Cisco ATA, and 0x0012XXXX for the Phone 2 port.
For fax pass-through mode, AudioMode should be set to 0xXXXX0015
for the Phone 1 port of the Cisco ATA, and 0x0015XXXX for the Phone
2 port.
When the Cisco ATA is configured for fax pass-through mode, all remote
gateways must be configured with modem/fax pass-through mode either
on a dial-peer level or system level.
Fax relay is enabled by default on some Cisco gateways. When fax relay
is enabled, it can override fax pass-through mode and cause fax failure.
Examples of the CLI commands to disable fax relay for IOS gateways are
as follows:
•
•
Some Cisco gateways (such as Cisco VG248, and Cisco 6608) may use
signaling messages based on RFC2833 for G.711 upspeed when loaded
with older software images. This method is incompatible with the Cisco
NSE-based method.
You must check to make sure that the image on your gateway supports the
Cisco NSE-based fax/modem pass-through. Otherwise, you must
configure the Cisco ATA to use fax mode.
The Cisco ATA has a configurable NSE packet payload-type value whose
default is 100. This value is compatible with the implementations of most
Cisco gateways. However, some Cisco gateways use 101 as the NSE
payload type.
Ensure that all gateways in your environment use the same NSE payload
type if you wish to successfully use fax pass-through mode.
prserv Overview, page 6-8
Analyzing prserv Output for Fax Sessions, page 6-9
fax rate disable for H.323/SIP gateways
mgcp fax t38 inhibit for MGCP gateways
Chapter 6 Configuring and Debugging Fax Services
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