I don't use the pay services that will track cell phones, but I do use whitepages.com, radaris.com (but I think they just changed to an everything costs money thing, yp.com whitepages to find land-lines or "listed" cell phones.  

.), to set boundaries on hours when you will accept calls, consider a business phone line that is separate from personal cell and perhaps hire a helper to assist with simple, tedious tasks like posting ads and initial screening. 

If someone asks about it a few hours before I will just tell them to come and not get anything more than their name and a cell number in case I have to cancel last minute.

@Raul Pedrozo I have had tenants not respond to texts or calls only to find out their cell phone number changed or they didn't recharge it.

And they'll get a cell phone and you can text them.  

@Charlie Fitzgerald, unfortunately, i only have her cell numbers and her email address.

If the problem is really bad, I would be willing to say consider a "car wash allowance" of say $10 a week which translates to say $40 a month of rent reduction...to me is easier than a car frame or self car washing.Speaking of particular tenants, I once had one who complained that her cell reception while inside is 2 bars instead of 4 bars as if this is something I have any control over. 

I know, I was a cell biology grad student.

We do not have such a thing since we use our cell phones for personal and landlord purposes. 

We only manage 2 ourselves, and when we're out of the country or on vacation where cell phones don't work well, we ask a family member to take the calls and give the tenants their number.