Is a technician's visit necessary to change operators?

Sometimes it is.

If you already have a line which is active at the time you change operators, the change of operators can usually take place without a technician having to come by.

If your line is not active a technician's visit may be necessary.

If you do not have a line a technician has to come by.

Please ask your new operator if a technician has to come by and if so, how much it will cost.