service door
service entrance
servant's entrance

When they hit the lower landing, the door for the service entrance was right in front of them.

He did not move until she disappeared through the service entrance.

David brought his car around to the service entrance and they loaded up.

I looked around and a second later saw her slip out of a service entrance ten feet away.

She went to the service entrance and opened the door.

A moment later she came to a halt at what was clearly a service entrance.

He knew there had to be some sort of service entrance.

The driver walked the woman into the building through the service entrance.

"Right here's fine," I tell him as he approaches the service entrance around back.

Go into the building's service entrance and ask to speak to the super.