The tech probably doesn't care that much; his system still shows him as on the phone.
Having worked in a variety of call centers, it's going to depend. ACL (average call length) was a common metric, and if it goes too high, it can draw attention. At Gateway during the "lets screw up our reputation" era, call center workers could face disciplinary action if ACL went above 13 minutes. Of course driving such metrics like that leads to worse service and customer satisfaction, but at the time the new CEO didn't care about such things. He just cared about making customer service appear more efficient as a cost savings measure. This was after all the same person who loved CCS, Client Conferencing System. Why only have one customer on the line at the same time when you can have 4 or 5, maybe even 6 all trying to be helped at the same time by one tech.