I've used my cell phone as my one and only business line for several years now.
I've never lost a customer to static or service dropping out in a given area. I don't think I've ever had any customers view me as a vagrant lawn care guy, but rather see me as being more attentive by being able to respond to calls even while out in the field.
There have been many, many times when a customer would call and I just happened to be a few blocks away and could swing by and take a look at a new property. That kind of response time is impressive to new customers. The same thing has happened when a customer with a problem. And I was close enough to run over and solve it.
Also, as a general rule of thumb, I've found that I need to run my business only during certain hours. If I don't, I never get any down time to myself. That's when I can just turn the cell phone off and everything rolls over to voice mail.
My phone is with Cricket. I pay $35 per month and it's unlimited local calling.
If you wrestle with a hog, you both get dirty. But the hog likes it.