Have Digital phone Service have you changed the default Passwords?.

One of my customers recently had a problem. He was not getting   phone calls from his  normal and prospective customers  at his business it seemed from a certain area code, even thou he had heavily advertised in the area . Ends up after calling  around to his  regular customers in area after not even hearing from them he found out his phone number  he set up special for them to call was being blocked ,and telling callers the number was no longer accepting calls.
He called me as I provide him phone services to the stores and when I determined it was not the AVAYA phone equipment I maintain for him that it  was his provider Comcast/ Xfinity  I called them and when a technician looked into it one of his store employees had turned on the block using the default password provided by Comcast because he was tired of taking the calls . My customers daughter who was in charge ordering and administrating  of the lines  had never changed  them from default  pass word  and the employee using the default pass word just turned off the line using a * number command .
My customer immediately fired the employee for doing it  This action by the employee cost him several thousand dollars in advertising money and thousands more in sales and lost customers.

This is not the first time I have run into problems like this where an employee also one time had changed the hours of operation on the voice mail that they where not open  on certain days at another business I take care of  as well as an employee who un did a dialing restriction on certain lines in a customers business and made thousands of dollars in unauthorized overseas phone calls. .
 Leaving default passwords on Phone lines and systems  in today's modern world is a bad idea and in the case of the line block my customer sent in a letter and it is now not possible to use the * command to block lines and other features like call forwarding to prevent future problems. It is important to not leave default passwords in place on phone systems and phone lines where you have employees because it is just a matter of time till you have problems and that goes double for anything you have utilizing a computer chip like credit card machines , security systems etc.