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Feb 18 / Greg

Fire Panel Dialer to Grandstream HT818 ATA

I found myself in quite a pickle recently as a client needed a fire alarm dialer hooked up post haste for an inspection. I figured, “no problems, ire mon, bobsled.” Two and a half hours later it was working…perhaps it was more difficult than I thought. Here’s my config to get it working.

All of these configurations are done under the profile menu.

First is the DTMF method:

Priority 1 needs to be set to in-audio. This will take the DTMF tones and just shove them into the audio stream.
Disable DTMF Negotiate should be set to Yes so that it will grab in-audio and go with it.

Next is setting the codec to be used; Grandstream calls it vocoder:

Set “use first matching” to yes so it will use the supplied list.
Then set them all to PCMU which uses G.711U. Since this is the least compressed codec it is best for DTMF dialers.
I also set voice frames per tx to 10. It should be in a range of 2 – 10, and 10 seemed to work well.

Last is disabling echo cancellation:

First the dialer is a good distance from my ATA so I set the gain to -6 and Rx to -4.
Now disable both the Line echo canceller and the network echo suppressor.

After making these modifications and sacrificing two chickens everything started working. Good luck errbody!

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