The FCC now requires all new and replacement guest room telephones to have volume control.
The following questions were reprinted from the FCC website
As a hotel owner, must I replace all of my telephones with VC (volume control) telephones by a certain date?
No. As with workplace non-common areas, volume control telephones must be installed after January 1, 2000 when the first natural opportunity to replace the telephone occurs. Under the Commission's rules, these "natural opportunities" include: (1) any time the hotel or motel room is renovated or newly constructed; and (2) any time the telephone in a hotel or motel room is replaced, or substantially, internally repaired.
If new telephones are purchased or if telephones are replaced after January 1, 2000, hotel and motel owners must ensure that these telephones are HAC/VC.