Beep during Call

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Joined: Tue Jan 22, 2013 8:38 am

Beep during Call

Post by InTheAir » Tue Feb 05, 2013 6:29 am

Hello All,

Here I am back with another issue. During calls you will hear a beep, a DTMF beep, for no reason. I found this topic related to my issue but I find the answer rather interesting. ... all#p89856

It states that the problem is the volume on my phone. Why in the world would a phone that has been in use for a couple of years on a land line suddenly start doing this only when on the Ooma. If someone could give me a good technical reason why it happens on the Ooma but not on a land line then I will be happy. :D see!


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Re: Beep during Call

Post by lbmofo » Tue Feb 05, 2013 7:05 am

Search for "DTMF Talk Off" with quote marks.
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Re: Beep during Call

Post by murphy » Tue Feb 05, 2013 7:09 am

A landline phone system transmits the DTMF tone straight through its system to the called party.

Ooma detects that a DTMF tone has started, blocks the outgoing audio path, generates a new DTMF tone of the proper characteristics and duration, waits for the incoming tone to stop, then re-enables outbound audio. Apparently this is done because of the packetized nature of VOIP.

A DTMF tone is made up of two sinusoidal tone frequencies. The digit 1 consists of 697 Hz and 1209 Hz.

While speaking, if the DTMF decoder happens to detect this pair of frequencies, a DTMF tone is generated. The problem has existed since the invention of DTMF signaling. It happens more often to female voices than to male voices. Its called touchtone talkoff or DTMF talkoff.

Reducing the volume of the transmitted audio reduces the likelihood that the problem will occur.
Customer since January 2009
Telo with 2 Handsets, a Linx, and a Safety Phone
Telo2 with 2 Handsets and a Linx

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