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New Member

VG248 no Modem Answer Tone Detected

I have a VG248 connecting a modem to which a postage meter is connected. It works fine through a copper PSTN line. Call connects but you just hear the negotiation tone until the call drops. Traces from the VG248 indicate that it is not detecting the answer tone. Any suggestions on what to look for here?

6 REPLIES
New Member

Re: VG248 no Modem Answer Tone Detected

The only things I can think of to check are the passthrough settings on the VG248. Check the settings under Configure > Telephony > Advanced. Passthrough signaling should be set for legacy. Passthrough codec should be G.711-u-law. Those should be the default settings and they work for all our modems for credit card readers, postage meters, ATMs etc.

Hall of Fame Super Red

Re: VG248 no Modem Answer Tone Detected

Hi Von,

Here are a couple of docs to add to Chris's good post. Also, make sure the VG is running the latest version (1.3(1));

Improved Fax and Modem Handling Version 1.3.(1)

Many updates have been added to improve fax and modem handling on the VG248. These updates enhance the compatibility of the VG248 with other Cisco and third-party devices.

Previously, you could enable Cisco fax relay on a per port basis. Now, you can also:

Enable Error Correction Mode

Enable Non-standard facilities (NSF)

Modify the fax pass-through signalling

Change the Cisco fax relay payload size

Modify Cisco fax relay speed

Modify the Cisco fax relay playout delay

Some of these options are configured on a per port basis while others are configured for the device. For additional information about using these new fax options with the VG248, refer to the "Configuring Fax and Modem Settings" section of the Cisco VG248 Analog Phone Gateway Software Configuration Guide:

Configuring Fax and Modem Settings

From this VG248 Admin doc (VG248 Software Configuration Guide v1.3);

http://www.cisco.com/en/US/products/hw/gatecont/ps2250/products_configuration_guide_chapter09186a0080235150.html#wp1029049

Also this helpful doc;

Configure Fax Pass-Through with the Cisco VG248

http://www.cisco.com/en/US/products/hw/gatecont/ps2250/products_configuration_example09186a008020160d.shtml

Hope this helps!

Rob

New Member

Re: VG248 no Modem Answer Tone Detected

Von,

I do not have your complete topology, but I would make the following changes:

On VG248:

Advanced Settings:

Passthrough signaling should be set for IOS mode (instead of Legacy)

Port Parameters:

Caller-ID: Disabled

MWI: None

Call Supervision: None

On CCM:

Verify the above port specific parameters on each port in CCM.

Be sure verify the configuration on the far-end gateway (as the problem could be there).

New Member

Re: VG248 no Modem Answer Tone Detected

Thanks all for the responses. A little more info here.

Topology

Postage meter --> VG248 --> CCM --> H.323 --> 2811 --> PRI.

Have set the passthrough signaling to IOS. Codec is g.711.

Disabled Fax Relay on the dial-peers on the 2811.

All these have been set

Caller-ID: Disabled

MWI: None

Call Supervision: None

I guess I can try Fax Relay but I was really hoping to avoid that. If anyone has any other suggestions I'm open.

Hall of Fame Super Red

Re: VG248 no Modem Answer Tone Detected

Hey Von,

Just wanted to add this bug that I came across today;

CSCdv90121

Certain modem calls may fail if fax relay is enabled.

Certain modems, when connected to the VG248, send signals during operation that the VG248 detects as fax tones. If the VG248 is configured with Cisco fax relay enabled and the Cisco fax relay negotiation between the VG248 and the remote party is successful, a Cisco fax relay connection initiates between the two endpoints. However, this Cisco fax relay connection is not suitable for general modem traffic, and the modem call fails soon after it has been established.

The workaround for this problem is to disable the use of Cisco fax relay and to rely on fax pass through instead.

Hope this helps!

Rob

Re: VG248 no Modem Answer Tone Detected

Nice score on the bug Rob!

I have (4) VG248s running and so far so good. My biggest problem is the amphenol connection. I think my cabling vendor who installed my cables got some cheap amphenol connectors. We have them about as tight as you can make them on the vg248, but for whatever reason, they are not making good contact. You have give them a little nudge, then 24 ports start working.... it's annoying. We are having them replaced... but word to the wise, if you these cabled by a vendor, have them find the best you can.....

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