Cisco Systems 188 Analyzing rtpcatch Output for Fax Sessions, Fax relay mode Cisco fax relay mode

Chapter 7 Configuring and Debugging Fax Services

Debugging the Cisco ATA 186/188 Fax Services

–event 203, Modem Relay Mode, CM Tone Detected

–event Cisco Fax Relay (with RTP payload type 96)

–event Cisco Fax Relay ACK (with RTP payload type 97)

Analyzing rtpcatch Output for Fax Sessions

The following examples show the proper fax events when gateways are configured to operate in the following modes:

•Cisco ATA fax mode

•Cisco ATA fax pass-through mode

•T.38 fax relay mode

•Cisco fax relay mode

Example 7-1 Fax Mode

----------	FAX Summary 1 ----------
[	25]<2.131=>3.200>	Codec G711u
[	26]<3.200=>2.131>	Codec G711u

Analysis

Both sides use G.711 for the entire fax session.

Example 7-2 Fax Pass-through Mode

----------	FAX Summary 1 ----------
[	25]<2.213=>2.116>	Codec G723
[	26]<2.116=>2.213>	Codec G723
[	101]<2.116=>2.213>	Codec G711u/D
[	102]<2.116=>2.213>	NSE PT 100, EVT 192: Up-Speed,	CED tone Detected
[	103]<2.116=>2.213>	NSE PT 100, EVT 193: ECAN OFF,	Phase Reversal Detected
[	105]<2.213=>2.116>	NSE PT 100, EVT 192: Up-Speed,	CED tone Detected
[	107]<2.213=>2.116>	Codec G711u/D

Analysis

•Both sides initially use G.723.

•<2.116> switches to G.711µ-law using a dynamic payload type.

•NSE signaling packets are sent from <2.116>.

•An optional NE signaling packet is sent from <2.213>.

•<2.113> switches to G.711µ-law using a dynamic payload type.

Note EVT 193 may not appear for some fax transmission.

Example 7-3 Fax Pass-through Mode

		----------	FAX Summary 1 ----------
[			37]<3.200=>2.53>	Codec G723
[			41]<2.53=>3.200>	Codec G723
		Cisco ATA 186 and Cisco ATA 188 Analog Telephone Adaptor Administrator’s Guide (SIP)
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