I have had experience with both in-house and remote workers. It really depends on the tasks being performed. There is definitely no replacement for face-to-face discussions and teamwork at an office loaction. On the other hand, there are numerous technical issues that can be solved by remote employees.

For remote employees, unless your customers are paying by call, there would be no need to pay someone per call. I have usually setup pay based on experience and tasks that are performed. If a remote employee is not accomplishing the tasks they need to, then there is a problem. But babysitting to make sure their hours of work are completed will not work with higher level people.