Record your own voicemail greeting and listen to it as if you were a stranger with a problem. Most of them say some version of this:
"You've reached ABC Services. We're not available right now. Please leave your name and number and we'll get back to you as soon as we can."
Four sentences, and every one of them is working against you.
What each line actually tells the caller
"We're not available right now." The caller already knows. The phone rang out. What you have added is the confirmation that this was not bad luck, it is how the business runs.
"Leave your name and number." You are asking a stranger to do unpaid work on your behalf, at the exact moment they are least invested in you.
"We'll get back to you." When? This afternoon, tomorrow, Monday? A person with water coming through a ceiling cannot plan around that sentence.
"As soon as we can." This is the one that does the real damage. It sounds considerate and it means nothing, and everyone knows it means nothing.
Put together, the message is: your call is now in a line of unknown length, run by people who are not there. The caller has your competitor's number in the same search results, and calling them costs nothing.
The stat everybody quotes, and why it is not here
You will read that some large percentage of callers never leave a voicemail. That number gets repeated everywhere, and when you chase it back it turns out to be marketing articles citing each other. So it is not quoted here.
Here is what you can check yourself, today, for free. Look at your phone's call log for the last month. Count the incoming calls. Now count your voicemails. The gap between those two numbers is people who rang your business and left nothing behind, and it is your number, from your business, which beats anybody's statistic (more on that in what your missed calls actually cost).
Most owners have never done this. It takes four minutes and it is usually the moment the problem stops being abstract.
What a good greeting does
A greeting cannot answer the phone (when you do pick up, the first twenty seconds decide the call). What it can do is remove the three reasons people hang up: they do not know if you are the right business, they do not know when they will hear back, and they do not know what to say.
Say what you do and where. "You've reached Dave at Fairview Plumbing, covering Fairview and the north side." A caller who dialed the wrong Dave now knows in two seconds, and a caller who wanted you is reassured.
Give a real time, and make it one you will hit. "I'll call you back by six tonight." A time you can meet beats a warm sentence you cannot. If you only clear messages in the evening, say the evening. Underpromise and land it.
Tell them exactly what to say. "Leave your name, your number, and what is going on, and I'll come back to you knowing what I need to bring." Now the message is short, useful, and the caller feels like they have done something rather than shouted into a hole.
Give an out for genuine emergencies. If you have a second number or a text line, this is where it goes.
Something like:
"You've reached Dave at Fairview Plumbing, covering Fairview and the north side. I'm on a job and can't pick up, but I check messages through the day and I'll call you back by six tonight. Leave your name, your number, and what's going on. If it's an emergency and water is running, text this same number and I'll see it faster."
That is thirty seconds of your life to record, and it is the difference between sounding absent and sounding busy. Busy is attractive. Absent is not.
The things that quietly make it worse
A greeting recorded in a truck. Wind noise and road hum tell a caller you are hard to reach before you have said a word. Sit in a quiet room and record it once.
Music, jokes, or a long company story. People calling a service business have a problem. Every second before the useful part is a second they might spend hanging up.
A full mailbox. This is the worst one, and it happens to almost everybody eventually. The caller does not conclude that you are popular. They conclude that you have gone out of business. Check it monthly.
A greeting that is a year out of date. If it mentions hours you no longer keep or a partner who left, re-record it. Callers notice.
Where the ceiling is
A great greeting is still a greeting. It buys you the callers who are willing to wait, and it loses the ones who are not, which in most trades is a big share of the people calling about work they want done this week.
That is a real limit and worth being honest about. The greeting is the cheapest improvement available to you and you should make it this afternoon. It is not the same thing as answering.
The short version
Listen to your greeting as a stranger would. Cut anything that is not: who you are, where you work, when you will call back, and what to say. Give a callback time you will actually hit. Check your mailbox is not full. Then go compare your call log to your voicemail count, and see what the greeting is really up against.