I don't know the answer to your question, but found the following at
http://www.worldairportguide.com/airports/fra/fra.asp:
DISABLED FACILITIES
Facilities for disabled passengers include elevator and ramp access throughout the two terminals, automatic doors, adapted telephones and washrooms. Disabled passengers should inform their airlines of any assistance required prior to travel. The Fraport arrival service provides waiting rooms for disabled passengers (tel: (0)69 690 71276). The passenger transport company Behinderten – und Krankentransport Kaster (tel: (0)60 7481 4544) offers transport services for disabled travellers to/from the airport. Reserved parking is available. The Sky Line shuttle train is wheelchair accessible, while electric buggies are available in both terminals. A wheelchair-accessible bus service, equipped with an ambulance lift runs daily; a door-to-door transport service is also offered (tel: (0)69 979 8770).
Perhaps you could call the waiting room number above and ask.
PS: If you find out, please post here!