Cisco Systems ATA 188, ATA 186 Using rtpcatch to Analyze Common Causes of Failure, Analysis, 6-17

Chapter 6 Configuring and Debugging Fax Services

Debugging the Cisco ATA 186/188 Fax Services

•NSE signaling packets are sent from <3.200>.

•<2.53> switches to G.711µ-law using a dynamic payload type.

Example 6-4 T38 Fax Relay Mode

----------	FAX Summary 1 ----------
[	15]<2.53=>3.99> Codec G711u
[	486]<3.99=>2.53> Codec G711u
[ 1277]<3.99=>2.53>		Codec T38
[ 1278]<2.53=>3.99>		Codec T38

Analysis

•Both sides initially use G.711µ-law.

•Both sides switch to T.38

Example 6-5 Cisco Fax Relay

----------	FAX Summary 1 ----------
[	8]<2.53=>3.99>	Codec G711u
[	248]<3.99=>2.53>	Codec G711u
[	798]<2.53=>3.99>	NSE PT 96, Cisco Fax Relay
[	799]<3.99=>2.53>	NSE PT 97, EVT 192: Up-Speed, CED tone Detected
[	800]<2.53=>3.99>	NSE PT 97, Cisco Fax Relay ACK
[	801]<2.53=>3.99>	Codec C_FxRly
[	803]<3.99=>2.53>	NSE PT 96, EVT 192: Up-Speed, CED tone Detected
[	804]<2.53=>3.99>	NSE PT 97, Cisco Fax Relay ACK
[	805]<3.99=>2.53>	Codec C_FxRly

Analysis

•Both sides initially use G.711µ-law.

•NSE signaling packets are sent between <2.53> and <3.99>.

•Both sides switch to Cisco fax relay.

Using rtpcatch to Analyze Common Causes of Failure

The following examples show the rtpcatch output of failed fax sessions. <3.200> is ATA; <2.53> is a Cisco gateway.

Example 6-6 Cisco ATA Configuration Failure

----------	FAX Summary 1 ----------
[	37]<2.53=>3.200>	Codec G723
[	39]<3.200=>2.53>	Codec G723

Analysis

•<2.53> is the originating gateway and <3.200> is the terminating Cisco ATA.

•The Cisco ATA and the <2.53> gateway use G.723 codec.

Possible Causes for Failure

•The Cisco ATA is not configured with fax mode or fax pass-through mode.

•If the Cisco ATA is the gateway for a fax sender, the remote gateway is not configured with fax pass-through mode.

Cisco ATA 186 and Cisco ATA 188 Analog Telephone Adaptor Administrator’s Guide (SCCP)

Ol-3141-01 6-17