Hearing DTMF tones while on a call

Discussion in '3CX Phone System - General' started by infonetics, Mar 20, 2013.

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  1. infonetics

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    I have a new installation that is using a Patton 4114 gateway for their 4 POTS lines. While on a call, either outbound or inbound, both parties to the conversation can hear tones as if someone is dialing. Their old system is completely shut down and unplugged, and there are no fire alarms/security systems that are using these lines for anything that may be dialing out. Any ideas?
     
  2. leejor

    leejor Well-Known Member

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    I have also experienced that on occasion, when talking over PSTN Gateways. What I attribute it to, perhaps incorrectly, is the gateway mistaking a frequency in the voice as a DTMF tone, and then repeating it. I suppose it could also be an ATA, doing the same thing, but sending a SIP message to the gateway, which then generates the DTMF.
     
  3. infonetics

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    Update, I setup a vitelity SIP account on this server and routed all outbound calls through it rather than the Patton, and the problem hasn't occured on those calls. Inbound calls still route through the POTS/Patton, and are still experiencing the problem.
     
  4. leejor

    leejor Well-Known Member

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    That kind of points to the gateway generating the tone, doesn't it?

    I'm not sure what else, other than the keypad on a set, has the ability to generate DTMF.

    Google "DTMF Talk-off" , there are a number of sites about this.
     
  5. infonetics

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    Update #2 - I swapped one of the Yealink T26's for a Cisco SPA504G, and the Cisco is not experiencing the problem. I've also upgraded the firmware on the Patton 4114 to the latest version, but the problem still persists on the other phones.

    Yealink support has advised upgrading to firmware 6.70.0.140. I haven't had the opportunity to try that yet, but it is curious that the Cisco doesn't have the problem, while the Yealink does.
     
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