Mixing and Recording a Telephone Conference Call

Question

For a podcast project I'd like to hook up two phones with my Mixer.

In essence this works, however callers do not just hear me and other callers but also themselves which is obviously very annoying for an interview partner.

These are my current components.

• Alesis Multimix 16 FireWire (connected to a Mac Mini via FW)
• A PC acting as a phone (since the real phones seem to have trouble with the Mixer alltogether)
• FritzBox 7390 connected to a two channel ISDN line

The goal is that callers can hear me as well as each other but not themselves.

I consider using an external conference call service, yet the commercial ones are pricy and I don't trust the free ones. I've also thought about setting up some internal conferencing system, yet I'm not too experienced in fancy phone system building. But then again, I'd like to avoid a conference system if there's a better solution to this problem.

Does anyone know how to build such a setup? Is there anything I can build or buy? Is there a sofphone that can deal with the problem? So far I tried Linphone and Ekiga.

Answer 1

Don't try to do this with your mixer, the callers will get bad echos of themselves and have a hard time talking.

Instead, either use Skype's built in conferencing combined with SkypeOut to connect to POTS numbers. Or use another conference bridge service and PC based VoIP client. It should be easy to record the conference once you've brought it in to your PC/Mac.

Note that you should look up the legal requirements for recording phone calls in your location as well as each of your callers. It is probably a good idea to start the call by explicitly reminding everyone that the call is being recorded.

Answer 2

You need something called a telephone hybrid. It's a hardware box you connect the telephone lines through and has the option to "hijack" the line so you can record the audio from the (real) phone. This takes care of feed-back problems and so forth, and you connect it to the mixer with ordinary cables.

They come in many variants and for different regions, phone systems etc. For this reason I haven't listed any examples. You can however do a search in your local region to find one that match price and telephone system so are sure you get the correct one.

Answer 3

Use an auxs to send audio back to the phones, that way you can send separate mixes to each caller. For example feed caller 1 with aux 1. Turn up Aux 1 on every channel except the input from caller 1.