Cisco Systems ATA 186, ATA 188 manual Debugging FAX Pass-through Mode, Log event, Description, 6-10

Chapter 6 Configuring and Debugging Fax Services

Debugging the Cisco ATA 186/188 Fax Services

Table 6-2 Debug Log Examples (continued)

Log event	Description
[ch] codec: <pt1> => <pt2>	Voice codec switchover occurred. The voice encoder type switched from
	pt1 to pt2 for the channel ch.
	For example,	[0]codec: 4 => 0 indicates that the local voice encoder
	on the Cisco	ATA switched from G.723.1 to G.711µ-law.
[ch] Rx MPT PT=<NSEpt>	Channel ch received an NSE packet of event with payload type of NSEpt.
NSE pkt <event>	For event, c0XXXXXX indicates a CED tone event, and c1XXXXXX
	indicates a phase reversal event.
	For example, [0]Rx MPT PT=100 NSE pkt c0000000 indicates that the
	Cisco ATA received a CED tone event NSE packet with payload type of
	100.
[ch] Tx MPT PT=<pt> NSE	Channel ch transmitted an NSE packet of event with payload type of
pkt <event>	NSEpt. For event, c0XXXXXX indicates a CED tone event, and
	c1XXXXXX indicates a phase reversal event.
	For example, [0]Tx MPT PT=100 NSE pkt c0000000 indicates that the
	ATA transmitted a CED tone event NSE packet with payload type of
	100.

Debugging FAX Pass-through Mode

When the Cisco ATA is configured to use fax pass-through mode, the fax call session can be established with an arbitrary voice codec. Once the voice call has been established, fax machines can signal their presence by means of a CED tone or V.21 preamble flag, after which the gateways send NSE packets to initiate switchover.

Note For fax pass-through mode, check the Cisco ATA debug log to verify that it is acting as an originating gateway as well as a terminating gateway.

Terminating-Gateway Example

When the Cisco ATA is used as a terminating gateway for a fax session, make sure the following conditions are true:

•The Cisco ATA transmits CED-tone-event NSE packets.

•The encoder switchover to G.711 occurs during the NSE-packet transaction. An example debug log for a terminating gateway scenario is show below:

[0]Tx MPT PT=100 NSE pkt c0000000

[0]codec: 4 => 0

[0]Rx MPT PT=100 NSE pkt c0000000

Note The NSE response to the CED tone event is not mandatory; some gateways may not send back an NSE response.

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

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