While there seem to be no specific ruling on Modern Phone Booths, we refer you to the IFC: International Fire Code®: Is a member-focused association with over 64,000 members. It is dedicated to developing model codes and standards used in the design, build and compliance process to construct safe, sustainable, affordable and resilient structures. Most U.S. communities and many global markets use this as their standard practice.
Please see: Section 903.3.3
Obstructed Locations. “Automatic Sprinklers shall be installed in or under covered kiosks, displays, booths, concessions stands or equipment that exceeds 4 feet (1219 mm) in width. Most Modern Phone Booths do not exceed this size. However, some larger booths for 4 persons or more may require sprinklers installed. We highly suggest that you contact the Local Fire Marshall in your City, State for their ruling.
You may download a copy a copy of the International Fire Code 2015: https://goo.gl/wNnamg
Additionally, the NFPA National Fire Protection Association states
that no obstruction should installed within 18” of a sprinkler head. This should be considered when planning the lcation of your phone booth.
For additional information in your local area, please see the following: INTERNATIONAL CODE COUNCIL:
Most U.S. communities and many global markets choose the International Codes. International Code Council Members include state, county and municipal code enforcement and fire officials, architects, engineers, builders, contractors, elected officials, manufacturers and others in the construction industry.
Lastly, consult your Buidling Management for any addtional codes they may have for the buidling.