Vonage Fax issue with Unconditional Call Forwarding


While traveling, I forward my Vonage number to a landline when there is no high-speed data service available. People may still reach me via dialing my Vonage number directly, and thus not have to call multiple numbers, cellphones and so forth to reach me.

At times, I need to receive a fax, and after speaking to a given caller, will, on the same call, manually start a fax call at the same time that the caller does (ie, we talk, and say "Hi, I am going to send you the fax now", and then both press "SEND" and the fax goes through). I have been doing this for years (with Vonage acting as the effective "long distance" carrier) and it work fine.

Note that this is not via the VoIP modem from Vonage, but via call-forwarding from the Vonage number to a landline.In other words, it is NOT going through the Cisco ATA-186 (or other modems; I've tried a few; I just mention the Cisco since that is the one I offhand know by name), but instead a call comes into the Vonage number from a landline, Vonage rings the Cisco once, no one answers (with unlike telco-based call forwarding you can do on the single ring), and the call is then immediately ("unconditionally") forwarded to the destination number. (Thus, this is not a "*99" issue or a poor quality.high-latency internet connection issue problem, and so forth.)

Recently, however, within the past week or so (04/22/2007 and on), it seems that we try to establish the fax connection, the first overhead message containing the station ID is sent, and then right afterwards, when the actual fax data commences, -Vonage- disconnects the line. It is NOT the sending or receiving fax disconnecting (both sit there for some 30 seconds or more trying to re-connect), but that Vonage for some reason recently started disconnecting fax calls which are forwarded and not going over the VoIP modem.

We did some tests, and these were the results:

  1. Landline --> Vonage (fax connected to VoIP modem): Generally works fine (other than the usual problems that sometimes occur with VoIP faxing)

  1. Some other Vonage number --> my Vonage number --> forwarded to landline: works fine, no sudden drops of any kind

  2. Landline --> my Vonage number --> forwarding to Landline: Drops after Station ID info is sent.

  1. Landline --> Landline: Works fine

Thus, the only difference between 3 and 4 (the most relevant tests) is that in 3 the call is sent through Vonage as the "long distance" carrier and 4 it is sent via AT&T from work. (Our company does not use VoIP to send out faxes, so I am sure that number 4 was done with a traditional circuit-switched LD company).

This is NOT a problem for voice calls, only fax calls via forwarding.

After playing with this and replicating these results, Vonage was called, the problem was escalated to Tier III (?) support, and no one has yet to call back. (I am just SO surprised! ;) )

In the interim I tried something else: The lines from Interpage are via trunks which do not display caller ID. I connected a fax just now here to a regular Pac*Bell/ATT landline, made sure the caller ID was presented by hitting *82, dialed the Vonage number, which forwarded to a fax down the hall, and it worked fine!

After about 30 tests, with different faxes and different landlines, what seems to be happening is that IF you have a Vonage number unconditionally forward to a given fax destination, and someone calls it from a landline that is "Private" or where the Caller ID is not shown, that call will quickly fail during the fax transmission.

IF, however, the Caller ID is displayed or available, the call will work fine and the fax will go through perfectly!

As I stated, this started about a week ago, and Vonage does not have a clue about this. (Previously, it did not matter if the Caller ID privacy bit was sent from the originating party or not; all faxes would work fine.)

Can anyone else replicate this? (I only have the one Vonage line for my personal use)

Has anyone had a similar problem?

I plan to have someone call Vonage tomorrow to discuss this but was wondering if anyone else noticed it as well.

Please post replies here; however, I may also be contacted by going to:

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and selecting the "Web Submit" option, Attn: Bill.

Thanks in advance,


Bill DeBello Interpage Network Services Inc. (510) 315-2750

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(The views expressed here are my own and do not reflect those of Interpage NSI.)

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Regardless, it still passes though Vonage's VoIP network, which uses lossy compression (vs your telco, who very likely uses lossless VoIP)

Vonage has recently either increased the compression level, and/or changed the codec for call forwarded calls, I notice the difference on voice calls, so it isn't at all surprising that it would be exceedingly obvious to fax machines as well.

With the exception of services specifically designed for faxing (of which Vonage does not run one -- Their "fax line" isn't really aimed at faxing, just a different codec), VoIP and faxing don't play nice.

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