When a burglar or fire alarm is tripped, the central monitoring station operator will perform a check on the status of the system. This may consist of a visual check via cctv, or a call-back to the home or business to confirm the situation. Normally the home or business owner will need to respond with one of 2 codes identifying either an active situation or a false trip.
This is referred to as
>Alarm verification means an attempt by a monitoring company or its representative to contact a burglar alarm location or a burglar alarm user by telephone or other electronic means to determine whether a burglar alarm signal is valid in an attempt to avoid unnecessary police response before requesting law enforcement to be dispatched to the location
“Verified burglar alarm” means confirmation of an unauthorized entry or attempted unauthorized entry upon the premises, building, or structure protected by the burglar alarm system. Verification may be made by the alarm system user or other person at or near the scene of the activation, a private guard responder or alarm company operator, and shall be based on a physical observation or inspection of the premises, or by remote visual inspection of the premises.
California County code
So you could say that the operator verified the alarm.