I don't know why any recruiter wouldn't use an online scheduling tool to coordinate their phone screens. The only reason I can think of is that they just haven't heard of it yet.
If this is the first time YOU'RE hearing about online interview scheduling software, let me give you a quick introduction. Here's how it works...
Recruiter sets some basic parameters to maintain control such as "Don't allow same day appointments" or "Allow 15 minutes between interviews".
Recruiter finishes set up and obtains a unique web URL that they can send to candidates.
Recruiter creates an "invitation to interview" email template and embeds the link.
Recruiter sends candidates the email template when they want to schedule an interview.
Candidate clicks on the link, views the recruiter's actual availability and chooses a time that works best for them.
Recruiter and candidate get email notifications confirming the interview.
It's seriously that simple. If your cheap boss won't pay the $8 - $10 USD per month that it costs, I would recommend any recruiter in the world pay for it themselves. It will save 2-3 hours per week in phone or email tag.
And anyone thinking that it makes the candidate experience impersonal, I'd encourage you to talk to a candidate who has experienced the process. They're BLOWN AWAY. I can't tell you how many candidates and clients I've gotten on the phone with who say "Your calendar tool is really cool, what is that?" It's a great icebreaker.
Trust me on this one. The biggest improvement you can make to your recruiting efficiency this year for the lowest cost is to implement an interview scheduling automation tool.
It's easy, it's cheap and it works for any level of candidate.