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46. Hosting POTS Conference Calls With Your ISDN Codec   9/26/13 by Dave Immer

If you want to do a “phone patch” session in which talent gets recorded while multiple clients listen in, you can use a free service like and either be the host or a participant. Initiating a POTS call from your Zephyr, Suprima, RoadWarrior, Tokyo or other G.711-capable device is straight forward. On Zephyrs change the call type to Phone, on other codecs change the encoder algorithm to G.711.

But when the conference service asks you to enter access codes, the ISDN codec is unable to generate the DTMF tones required. To get around this problem you can download a free app to your mobile device that generates these “touch-tones.” For the iPhone get an app called DialPad. (It may also be available for Android.)

You will need a cable with an 1/8” TRS plug on one end and an XLR male on the other. From your iPhone headphone output go into a mic input on your mixer or codec but turn the gain down to around -25. Feed that input to your codec and confirm you are sending a strong level by trying the DialPad.

Initiate the call to the conference # from your codec. Now when you are prompted for the conference call access code, punch it out on your iPhone DialPad app and you’re good to go.