Mom and pop podcasts

One of the things I've wanted to do is interview folks over the phone. To do that, the first step was to find ways to make cheap telephone calls to any point in the world. The solution to that problem was to use a voice over IP service (VOIP), which I did. Many customers choose to connect a VOIP phone that plugs into their broadband router to act and behave like a regular phone. However, to be able to use the keyboard while conversing, I opted to use a free downloadable "softphone" -- a computer telephone -- which normally has an interface resembling a keypad displayed on the monitor. You then speak into and listen over a regular computer headset with a microphone, the kind you can buy in Radio Shack for about twenty bucks. There are few gotchas in setting a VOIP softphone, but not something that a two-fisted, hard drinking person can't solve. So the first part, making cheap calls to any point in the world, has a ready solution.

The second step was to find a method of recording VOIP telephone conversations (with the permission of the interviewee of course) and storing them as audio files. That turned out to be a little harder than capturing regular telephone conversations. To record a regular telephone conversation as an audio file, all you need to do is go down to the neighborhood electronics store and buy a fairly cheap pickup that will answer to the purpose. It takes the audio from both ends of a conversation and with a little more hardware record it in an audio format that can be saved to your trusty hard disk. Unfortunately, VOIP telephone conversations are not "telephone" conversations. They are actually packets transmitted in a particular protocol over the network. Therefore while Windows Sound Recorder, for example, will capture your microphone and headset sounds perfectly from the soundcard, attempts to record a VOIP conversation using the same method are doomed to failure. No amount of fiddling with input and output devices in the Settings menu will avail.

At this point one could go and get hardware that will essentially "tap" into the computer headset and record an audio file at the interface or shell out major bucks for a fully-featured VOIP recorder. These are typically manufactured for call centers so that they can record customer conversations for "quality control purposes". Heh. But unless one has a large and a half to shell out, getting a VOIP recorder probably isn't the best way to go. If your VOIP software happens to be a product for which a software recorder is available, then you can buy that for considerably less than a hardware recorder box. (Some software recording utilities are made for VOIP apps like Skype or Express Talk.) But if you, like me, use unsupported softphones then you must turn to capturing the VOIP network packets themselves.

This turns out to be easier than it sounds. The best approach is to download an open source packet sniffer, which is an application that will capture everything going through your network, including your VOIP traffic. Just turn on the sniffer when you make your call. Then having captured all the network traffic during the call, you filter the packets down to those of type rtp.p_type = = 8, which happens to correspond to the format of an a-law, u-law codec. (You might have to fiddle with the softphone to make sure it sends the packets in this format)  After applying the filters you will be looking at the VOIP call only. All the other network stuff has been filtered out. Then some packet sniffers (such as the one I downloaded) have the ability to assemble both the outgoing and incoming VOIP packets into one time stream which you can then save as .au or .wav file. And there it is. Your audio file is on your hard disk.

The last, optional step is to edit the computer audio file into something resembling an interview. That can be done by downloading free software like Audacity so that you can edit the interview itself. At this point you can dream of giving Rush Limbaugh or Howard Stern a run for their money. There, in a nutshell, is a guide to creating a podcast, which you can then get broadcasted in some fashion. The entire process described above requires no hardware other than your broadband connection, a soundcard, some hard disk space and a computer headset. Then, apart from your subscription to a VOIP service, the remainder is absolutely free. No money is required for the softphone or to record your VOIP conversations. Well not quite free. For those whose calling doesn't take them into looking at network traffic for a living it will cause some bother: a few hairs pulled in frustration and more than a few cups of coffee. I hope the readers of the Belmont Club find this post useful, even if it is slightly off the usual topic.

Commentary

Some readers will be horrified to discover that their VOIP conversations are actually visible as unencrypted packets over the network. But unless you take special precautions that's exactly what they are. Something to bear in mind if you're using VOIP over the company network with an intrusive IT manager.