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SPA122 not re-producing key tone sound on incoming calls

I am using a Cisco SPA122 ATA


I have an intercom phone that dials my SIP phone number. When I press 5 to allow entry, the door does not unlock. I have tested with my friend, had him call me, when I press 5, my friend does not hear the tone.


When I call my friend from my SIP phone, and I press the 5, he does hear the tone. Why does this only seem to work on outgoing calls and not inbound. Is there a setting on the ATA that needs to be set to get the tone to play on inbound calls?

Dan Lukes

It sounds like DTMF issue. There are various (tree) methods to pass DTMF thru SIP. All devices on the path needs to be configured to understand method of it's peer on the path. So check configuration - phone should send DTMF using method recognized by it's upstream peer. It needs to be verified for all devices on the path.


Thanks for this, I am testing now. The SPA122 by default has the DTMF set to auto. SIP provider use RFC2833 (AVT), so I have set my ATA to use AVT.



The changing the DTMF mode made no change to the issue, tried all options available.

To explain issue in greater detail:

  1. Person calls me from my intercom system to my phone number.
  2. ATA (phone attached to SPA122) rings.
  3. Talk to person, and then press 5 to unlock front door.
  4. No tone is played that can be heard on the other end.
  5. Front door does not unlock.

Is there a way to get the tone when I press the 5 key. This is all that is required from the intercom system to unlock the door. Even if I call my number to ATA directly from my cell phone, when I press 5 on the ATA line, I do not hear it on my cell phone.

@Robert41794 wrote:

Even if I call my number to ATA directly from my cell phone, when I press 5 on the ATA line, I do not hear it on my cell phone.


For what is worth, I ran a test on my SPA122 looking to see if pressing the 5 button on the called phone (attached to the SPA122) could be heard on my calling mobile phone. I tried changing various DTMF settings on both my SPA122 and voip provider ( I could not get it to fail.  The problem could also be in the mobile phone leg of the call


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