I had to stay in a shelter once, about a year and a half ago. It wasn't specifically a DVS, but many of the women and children there were victims of some sort of violence. If a call came in at the downstairs reception office for one of the residents of the shelter, the secretary was not allowed to either confirm or deny that the person was in residence there. A message could be taken, with the caller informed that the receptionist would forward it to staff. The only way a call could be put through to a resident was if it came in on the private line that was solely for the use of the residents (an unlisted number).
It was the same for packages/mail that came in to the downstairs office. If the mailperson had a question about the addressee of the package as to whether they lived at the address, it could not be answered. The package/mail simply had to be left at the office and subsequently delivered to the resident by staf
However, if LE came to the shelter to question a resident about possible involvement in a crime, they had full access to that resident. The person in question would have to meet with LE either downstairs in the office area, at the police department or in the parking lot of the shelter. LE only came into the actual shelter itself on very rare occasions.
If the person LE was looking for had already left the shelter, staff was allowed to give forwarding information for that resident. It is the only instance I know of where they were allowed to do that.