If it's important enough that someone needs to get a hold of me they should be having a human calling that can follow through with that simple request.
We get a LOT of people who do something similar to you, or just leave their voicemail box full, or don't bother to set up voicemail at all. Then they get angry at us: "Why didn't you call me to let me know my system was finished?" "We did, and you didn't answer." "Oh, I don't pick up calls from random numbers." Well, I don't know what to tell you, then...
I can't text you, because we don't have a business cell phone to text with. Yes, I suppose I could set up some fancy integrated-with-our-POS system to text you from some number that we could then read replies to, but that both would cost time and money to develop, and would open up yet another vector for us to be contacted by (we already have a phone number, Yelp messages, Facebook messages, and email as it is.)
We can (and do) email customers, but email presents its own issues: People like to reply to them and we don't always have time to respond quickly, and people don't check their email often, or it goes into a spam filter...
It's not just us. It's your doctor, your pet groomer, anyone who has a local business. My suggestion here is to pick up calls from your local area code, and/or program into your phone the businesses you do business with.
Text messaging with or without email is easy to access online[0] and no longer required an ancient "business line" - you don't need to "integrate" it into your p.o.s. POS either. If you have fb, then there's surely no reason other than will that you can't use SMS.
[0] for example, https://www.twilio.com/
It's worked so nicely since I got it, I'm surprised we ever did without it. I think it also auto-disconnects calls from numbers that a sufficient-amount of people have flagged as spam.
The only problem it doesn't solve is when a business decides to do it's surveys/telemarketing through the same number it attempts to contact clients on. This is especially rife with SMS spam, where they use the same number to SMS you valid "updates" that they use to send promotions/ads and other spam.
This only weeds out lazy robocalls, I get plenty of calls with (presumably spoofed) caller id from my exchange. It would be trivial to add that into a spam script.
You can set up a virtual number to receive incoming - and so do 2 way email - SMS, and (not sure this applies in the US) if you don't need 2 way can spoof your number to show text alert instead, eg the text shows as from "1Up Repairs".
In your position it definitely sounds worth exploring. There's a lot of other places than Twilio too.
One last hint, if they're "too cheap" they'll be using grey routes and should be avoided like plague.
When a business, local or otherwise, asks me for a phone number I regard it as a spam-vector and decline. It's the businesses that need to adapt, not the customer.
A phone number is a very personal piece of information given the intrusion it permits into one's life, and many people are hesitant to share it with one-off requestors for that reason.
Why aren't you tweeting 'job #3327 complete'?