A professional phone call is a meeting. It doesn't carry as much seriousness as an in-person meeting (one of the reasons I suggest starting with it in Email Anybody and not just jumping right to a meeting). But you should still treat it with the seriousness of a meeting.
Given that more people work remotely now and people just talk on the phone less, it seems like the norms and rules around phone call etiquette need to be spelt out.
Here are my basic professional phone call etiquette rules:
1. Send a calendar invite
A professional phone call is a professional meeting. You should try to be on time and treat it just like you would treat a professional meeting.
If you went to a professional meeting, you would send the other party a calendar invite (or request that they send you one). Do this for your phone calls.
Make it clear who is to call whom and how they are to do it.
If the other party is to call you, list your phone number in the invite.
If you're to call the other party, say that and, for your own purposes, paste the other party's phone number in the invite if you don't have it saved in your contacts.
Here's an example of how my calendar invites go out when scheduled through Calendly:
This doesn't have to be fancy. It just needs to work. This way, if the other person forgets to call you, you haven't given them an excuse. And you've made it easier for both yourself and the other person.
Protip: If the other person doesn't volunteer to send a calendar invite, try to always send it right after you confirm the meeting. You want to be the kind of person who sends calendar invites quickly and makes the other person feel like you're on top of your shit.
2. If you're going to be late, let the other person know
When I worked with Isaac Morehouse in a tiny office in Charleston, SC, I vividly remember how punctual he would be with his calls.
If he had a call at 3 PM, he'd be at his desk at 2:55.
At 2:57 he'd have his phone out and the number he was to call inputted. He'd sit and watch the clock change to 3:00 and make the call when that time came.
Isaac understood that phone calls are meetings. They are just meetings that don't happen in a conference room. So treat them like you would a meeting in a conference room. If you're running late to a conference room, keeping somebody waiting in fluorescent lighting with bad coffee, you'd send them a quick text or email letting them know you're running late.
Why wouldn't you do the same thing with a call?
90% of the time, the number you're to call for a meeting is a cell phone, so you can reasonably assume that if you text that number, the person would see it while waiting for your call. The text can be simple:
"Running just a few minutes late. I'll give you a call shortly."
There you go. That's it. That tiny courtesy lets the other person know that you at least are aware of the fact that you're keeping them waiting. It lets the other person know they can go get a cup of coffee, or finish sending an email, or even putz around on YouTube while waiting for you to call.
3. If you miss the call, you are not owed another one
Stuff happens. People understand that you might get stuck in traffic, or somewhere without reception, or that you just forgot about the call. If you miss a call, explain why you missed the call.
But also know that you are not owed a rescheduled call, especially in the cases where a Very Busy Person (more about them in my book) takes time out of their day to talk to you as a favor.
If you miss the call, apologize, explain why, and ask them if they'd be willing to reschedule with you.
If they say no, don't get angry. Just thank them for the first chance and tell them you'd love to gain that opportunity back in the future.
4. If you're going to be on speakerphone, make it clear at the beginning of the call
One of the oddest things I've experienced on calls is talking to somebody and 10 minutes into the call hearing a new, third voice on the call who was listening the entire time. Turns out the call was on speakerphone (or worse, it was a conference call and I didn't know) and the other person never made this clear.
Don't drop a bomb on people this way. Tell them if you're going to have other people on the call.
Again, calls are meetings. It would be weird for you to sit in a conference room with somebody, start talking to them, and then have a colleague who was listening the whole time blurt something out on a hidden speaker.
Don't do this. Be open and transparent with people so they know what they have to say and what they shouldn't say.
5. Be in a quiet place or use quality headphones
AirPods are the best possible purchase for somebody who likes walking meetings.
Somehow, some way, the microphones in them are pretty good at filtering out background noise from the street or other people nearby. You can talk to somebody on the phone with cars driving by without them hearing the cars.
If you don't have AirPods or a good pair of headphones, schedule your calls so you can be in a quiet place when you take them.
(I say good headphones because most headphones are not good. You can usually hear when somebody has bad headphones because a gust of wind or the shuffling of their coat picks up, is transmitted, and amplified directly into your eardrums.)
It's rude to put yourself in a noisy place, put the burden of hearing through your noise on the other person, and then ask them to speak up when the noise pollution around you makes it hard for you to understand them.
Same goes for calling customer service:
6. Put on headphones or AirPods before the call starts
This goes in with point 5. It's just rude and annoying to hear somebody shuffle around with their hands to put in headphones after they've answered the phone.
"Hey, just give me a sec. I need to put in my headphones."
"Sure, okay." Thinking: Dude, you knew I was going to call. Why didn't you put them in like 60 seconds ago?
(I am guilty of this one more often than I'd like to admit.)
7. Answer with your name
If you're calling somebody for the first time and haven't talked to them before, don't just say, "hi!"
Same goes if they are calling you for the first time.
The worst is this:
[Be you, calling somebody for the first time.]
Other person: [Answers] Uh, hello?
You: Uh, hey, hi, this is Zak.
Other person: Zak?
You: We had a call at this time.
Other person: Oh yeah! Hey!
Most of this is obviated by sending a calendar invite with your phone numbers in it. But it's also obviated by both parties internalizing good etiquette by answering with their names.
It can be as simple as, "This is Zak." Or more polite as, "Hi, this is Zak."