When you can't make it in person, you can choose to record a phone call instead. That said, phone calls are really tough to listen to for long periods. So you need to keep your interview super focused, and edit it so that you reduce the gaps.
There are several ways to record a phone call. Perhaps the simplest is to record a speakerphone using your microphone. This method can produce surprisingly good results. Put your phone on speaker and use a microphone on a stand between you and the phone. Then use your recording software to capture the signal. You should also mute the speaker on your computer to avoid feedback.
If that doesn't get you the results you want, then you will need some hardware. The first option is a handset tap. The QuickTap from JK Audio (Figure 6) is around $60 and fits between the phone base and the handset. There is an analog audio output that you connect to your computer. In order to make this work you need a traditional wired handset. It will not work with a cordless phone or a handset with a dial pad. A new handset tap called the USB Blast R-1000 (Figure 7), about $129, connects directly to a Windows computer by USB and includes recording software.
Figure 6 (left). Inserted between your phone's handset and base, the JK Audio QuickTap provides a mono mix of the caller's voice and yours on a 1/8-inch jack.
Figure 7 (right). The USB Blast R-1000 is a handset tap that connects directly to a Windows computer's USB port. The device itself is smaller than a floppy disk.
The second option is a coupler. Couplers fit between the phone and the wall jack and record the signal on that line. Once again there is an audio output that connects to your computer. With a coupler you can use a cordless phone, though you may not want to, for audio quality reasons.
The last option for recording phones is the hybrid. A telephone hybrid is a full acoustical setup that has one connection for the phone line, then an output for the signal from the caller, and an input for your microphone signal. A hybrid is what talk-radio stations use to connect their callers into the audio system. Hybrids can costs thousands, but recently companies have been developing smaller hybrids for amateurs. JK Audio has a product called the Inline Patch ($270 list) that provides separate outputs for your voice and the caller's, although the signals aren't completely discrete, just 20dB different in level.
Note that in the United States, each state specifies whether one-party or two-party consent is required for legally recording a phone call. To be safe, just ask the interviewee at the beginning of the call if they consent to being recorded.
Another way to get an interview at a distance is to use a Voice Over Internet Protocol (VoIP) service like Skype. Several articles have been written on recording from Skype on both Mac and Windows, so I won't cover it in detail here. In addition, the newest version of Apple GarageBand (v3) can record a conversation from iChat.
You might be asking yourself, "I've listened to a lot of interviews where I know these people aren't sitting in the same room, but the audio is really good; how does that work?" What you may have heard is a two-ender or double-ender. The technique is fairly simple: you call the interviewee and do a phone interview with him or her. At the same time, on both ends of the line, you both are recorded using high-quality recording setups. The files from both sides are then brought together in a sound editing program and synchronized. The telephone audio itself is never recorded.
The upside of this technology is that, when it works right, the audio quality will be better than you get with the phone. The downside is that it almost never works right. Sometimes you get disconnected; other times the interviewee's connection will go down. And when that isn't happening you will get pauses or strange audio edge effects from the signal.
Whatever setup you use, you need to triple-check the whole system before you go out into the field. Did you bring extra batteries? Did you bring extra cables? Did you do a dry run the night before? Do it. Or you will regret it when you get home and find yourself with a zero-length file that should have been a once-in-a-lifetime interview.
Before you hit the Record button, there are a few questions you should answer for the person in the hot seat: How long is the interview going to be? Will the interview be edited, and if so, how much? Just the "ums" and the pauses, or will you be editing for content by moving or deleting whole sections? The interviewee will want to know who your audience is and what they will expect from the interview. You should make most of this clear in your pitch letter or subsequent pre-interview communication.
The interviewee might also want to know what the first question will be, and for most friendly interviews that should be fine. One of the more common ways to build a killer interview is to start with a stinger question that gets right to the heart of the matter, then to reel back to some background questions and build up to a punchy conclusion. That will engage the listener right away. I don't know about you, but my eyes roll back in my head if the answer to the first question starts with, "Well, I was born in...." You want to grab the user from the get-go.
On your end, you should have a good idea about what the interviewee wants to get from this interview. Is it a plug or two for his recent masterpiece? If so, provide a softball question or two for him to hit out of the park and some time for him to insert an obvious plug. Again, ask ahead of time what topics your interviewees would like to cover—and whether there's any background material they'd like you to read first.