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New Member

Translate In-Call DTMF Tones

I am using IP phones (Polycom 601's) that are not capable of sending a hookflash (DTMF event #16). I was wondering if I could have the gateway (a 2620XM running 12.4) listen for a standard DTMF (or combination thereof) tone (0-9, *, #) and send out via an FXO port a hookflash. Is this possible?

New Member

Re: Translate In-Call DTMF Tones

Are you sure Polycom 601s CAN'T send hookflash? I found this excerpt from the Polycom site, if this is the phone model you are referring to:

The FLASH button on the SoundPoint Pro functions like tapping the hook button on a standard telephone one would find in their home. In North America, the SoundPoint Pro's flash button places the unit on hook for exactly 600ms. This time will vary between 100, 300, and 600ms based on the appropriate region of the world's expectations on flash/hook.

(Here is the link:,/?St=26,E=0000000000004371619,K=7443,Sxi=12,Case=obj(33518)

If the FLASH button works as an equivalent to the hookflash on a standard phone, all you would have to do is configure your router's hookflash timing to coordinate with the timing used on the Polycom. If you have a test environment, I would just experiment around with it, and run CCM traces to see if the timing matches between the phone and the router. Also, here is a reference to using Hookflash Transfer with MGCP,along with a sample of the CCM trace output for a SUCCESSFUL call if you are using CallManager.

If you still want to try what you are suggesting instead, you can set this up on an H.323 gateway. here is a sample:

dial-peer voice 1 voip

incoming called-number .

destination-pattern 200

dtmf-relay h245-signal

dial-peer voice 2 pots

incoming called-number .

destination-pattern (your DTMF string)

port 1/0

voice-port 1/0

timing hookflash-out 600

connection plar opx 200

** I can't guarantee this is going to work because, I know if you try this with an FXS port and an analog phone attached, it WON'T work, because the hookflash signal is sent as a break in the loop and CANNOT be sent as an audio signal, but is actually sent as "!" by the router, using the H.245-signal DTMF relay.

Good Luck and let me know if any of these scenarios work for you....

New Member

Re: Translate In-Call DTMF Tones

Unfortunately a SoundPoint IP 601 does not have a FLASH button. I've already gone back and forth with Polycom's tech support on this topic. They assured me that the IP phone does not have a provision for FLASH. In fact this is from the last email I received from them, "The phone can only generate RFC 2833 (DTMF only) events for 0--9, * and #." Also, if this is important, I am not using CCM and I'm using SIP.

As for the dial-peer's, don't they only play a part during call-setup? I didn't think they can also be applied while a call is in progress.

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