Plus, a phone call tends to sound like an Edison wax recording on TV, even with the best cell or landline connections.
But just as the networks seemed to stiffen their backs against Trump, Democratic front-runner Hillary Clinton has started playing the phone game in earnest, too. Clinton did back-to-back phone interviews with MSNBC and CNN last Wednesday and another with CNN the week before.
If anything, Clinton's increased use of the tactic raises the stakes for the networks; there are now effectively only two major political "gets" for cable and broadcast news programmes, which means Clinton and Trump have the leverage to dictate the terms of any interview. It could leave TV-news producers with a dilemma: Should they play ball with the two leading presidential candidates or hold out for a face-to-face interview only?
Fox News's Chris Wallace knows that holding out has a price. In August, as Trump was phoning the Sunday talk shows, Wallace stood firm and decided that Trump had to appear on camera if he wanted to be on his programme, "Fox News Sunday". Trump declined - and Wallace lost the chance to speak to him for the next two months. The decision, he said, cost his show some ratings; even on the phone, Trump could boost a programme's Nielsen numbers.
But Wallace maintains that "the Sunday shows occupy a unique place. They're the place for long, in-depth, probing interviews with the candidates. The idea of appearing by phone strikes me as debasing the currency of what the Sunday shows are all about".
The venerable US Sunday programmes "Meet the Press" on NBC and "Face the Nation" on CBS have since adopted similar bans on phone interviews (ABC's "This Week With George Stephanopoulos" still permits them), a trendlet that encourages Wallace. "I'm glad they got religion along the way, and I welcome them into the fold," he says.
Network people point out (perhaps a bit self-servingly) that phone interviews aren't as effective for a candidate as being in a studio. What an interviewee gains in media ubiquity and ease over the phone - no hair or makeup necessary, no waiting in the green room for a scheduled time slot - he or she loses in impact, they say. "We think [an in-person interview] is a far better and more illuminating experience for viewers," said CBS News spokesman Richard Huff.
But other hosts say a ban on phone interviews makes little sense; viewers want to hear from the candidates even if they can't see the candidates.
Jake Tapper, the host of CNN's daily programme "The Lead," prioritises the choices this way: "In person is always preferable to satellite, and satellite is always preferable to phoner, but as I learned as a print reporter, I'd rather have the phone interview than nothing," he said.
"Meet the Press" host Chuck Todd has previously said that he'll no longer do phone interviews on the Sunday programme but will do them on "Today" or on his daily MSNBC show. The difference, according to the network, is that the daily interviews are briefer than the Sunday sit-downs, and that the candidates' travel schedules may make it difficult to get them in front of a camera during the week.
In person is always preferable to satellite, and satellite is always preferable to phoner, but as I learned as a print reporter, I'd rather have the phone interview than nothing
Of course, technology has made the "can't-get-to-a-camera" excuse a bit hollow these days. Inexpensive video connections are available virtually everywhere via Skype, Periscope, Meerkat or FaceTime, although the quality of such transmissions might be another issue.
Like Fox's Wallace, the producers of "CBS This Morning" have held out against the phone, declining several phone-interview offers from Trump's camp. The programme did make one exception for breaking news: In the aftermath of the Brussels terrorist attacks in March, it broadcast an audio clip of Trump commenting on the news with CBSN, the network's digital streaming news network.
But Wallace contends that there's nothing like mano-a-mano.
"My feeling is that except in extraordinary circumstances, we should force the candidates to come on," he said. "We have to maintain our standards and be true to ourselves and not compromise."
