Since I've been doing radio spots for my work, it was only natural for me to also record our telephone "Event Line" (a listing of our upcoming performances). Naturally, I figured that simply using the same method I'd been using for the radio spots should work fine, with the addition of holding a phone or headset up to a speaker. The results were less than spectacular, to say the least.
After doing some research, I found a way to interface an audio device (such as a computer line out or an output from my M-Audio Fast Track Pro) with a telephone line. For less than $20, I built such an interface. Here are the items I used (from RadioShack):
279-391 Modular-to-spade 12" line cord (clearance item, but my local store had it)
274-658 4-Position Barrier Strip (for neat connection of the wires)
273-1374 1:1 Isolation Transformer
42-2372 12-Ft. Shielded Cable, RCA Plug to Tinned Wires
270-1802 Small Project Enclosure (so I don't have to see the bare wires)
274-320 Mono Phono Jack to 1/4" Mono Plug Adapter (2-Pack) (gives me the option of either an RCA or 1/4" phone jack output)
Here is how to wire the line cord, transformer, and audio cable:
To use the interface, I first called the voicemail number (on a cordless phone) and went through the key presses necessary to actually record the greeting. At just the right moment, I plugged the 1/4" phone plug into the headphone output of my M-Audio Fast Track Pro (the telephone interface was plugged into a different outlet from the cordless phone). After some trial and error, I figured out that I had to unplug the homemade interface to able to use any of the touch tones after I played the audio file (the interface "seizes" the line after it is plugged in, like a music-on-hold device). After more experimentation, I got a decent-sounding greeting, complete with background music.
Though somewhat content with the above solution, I figured there had to be a way to send sound directly from my computer to the voicemail server. I found a such a method—Skype. I set the microphone in Skype to be the Creative Audigy 2, and in the Audigy 2 control panel, I set it to use "What U Hear." You can figure out the rest....
With either of the above solutions, don't be surprised by the lack of audio quality—telephones only use the 300-3400 Hz frequency range. As I discovered, it's best for the source audio file to be EQ'd to sound like telephone audio (full-frequency content only adds distortion to the greeting). For this, I used the 15-band EQ plug-in for Audacity.
Just to play around with Skype, I called Brandon, but instead of using a cheapie computer headset, I used my voice-over recording setup (MXL DRK microphone, M-Audio Fast Track Pro, and a pair of Koss Pro4A headphones). Brandon (and his wife) noted the richness of the sound quality compared with me calling from a normal phone. I also called a couple of other friends, and they also noted that. Of course, that setup is a bit overkill for Skype.
