My parents had this exact problem. They had no dial tone on their old POTS Verizon service. They called Verizon and were given a service appointment for 10 days from then!
That is unacceptable, especially for my parents, who really need/use a landline.
Needles to say, I got them to switch everything to Brighthouse.
The port was fairly painless, as long as you have your install on a WEEKDAY. Porting usually only occurs during the week, so Brighthouse has to put some gadget on your line to allow your phones to use your old line until the switch happens. In your case, as was my parents, the old line was dead, so the porting couldn't happen until Monday and the gadget wouldn't work, but in the end it was resolved Monday morning and my parents are now setup and happy with Brighthouse for TV/Internet/Phone.
As BHNTech said, let Brighthouse take care of everything and call Verizon the next day to cancel their service.