Hi John,
If you pick up the call that looks like it's coming from the rep, you'll be monitoring the call. That's expected behavior and happens with certain kinds of phones:
"When using a supported SIP phone the system automatically answers your phone, enabling the monitor session. When using a remote number or any phone provisioned externally to PureCloud, the phone will ring and require you to pick up to start the monitor session."
From https://help.mypurecloud.com/articles/monitor-in-progress-interactions/