The call letters of the Wanamaker store station in Philadelphia, Pennsylvania were MHE. (At this time, all Marconi stations worldwide had callsigns starting with the letter "M"). The coast stations mentioned in this review, all but one of which were operated by the Marconi company, include: Sea Gate, New York (MSE), Cape May, New Jersey (MCY), Virginia Beach, Virginia (MSY), Fernandina, Florida (MSF), Key West, Florida (U.S. Navy station NAR), Sagaponack, New York (MSK), Siasconset, Massachusetts (MSC), Camperdown, Nova Scotia (MHX), and South Wellfleet, Massachusetts (MSW).
 
What to See in Philadelphia, 1911, page 38:

The  Installation  of  the
 
MARCONI  WIRELESS  TELEGRAPH  SERVICE
IN 1878 the Wanamaker Philadelphia store was the first to be equipped with electric light. Wanamaker's was the first store to install the telephone as an essential part of its service to the public and later (1905) the all-night telephones.
    In 1911, Wanamaker's, faithful to its aim continually to increase the public convenience, is the first store to be equipped with

Wireless   Telegraph   Service

    These wireless stations are now formally dedicated to the public service as official stations of the Marconi Wireless Telegraph Company, and will be open for the receipt of messages during the hours the Store is open.
    Messages will be received for steamers at the Western Union Telegraph office, on the Main Floor, Central, near the post office, in the Wanamaker Store. Communication can be had with ships 150 or more miles away whenever such steamers are fitted with a Marconi apparatus. Messages will be charged for at the regular rate, $2 for the first ten words, and 12c for every extra word. Address and signature free of charge. In case of ships at greater distances from this station, messages will be sent via the following stations at rates given here:
 
COAST  STATION     Rate     No. of
Hours Out
     From Port of Arrival
or Departure
Sea Gate, N. Y. $2.00--12       4       New York
Philadelphia, Pa. 2.00--12     4       Philadelphia
Cape May, N. J. 2.00--12   10       Philadelphia
Cape May, N. J. 2.00--12   24       Baltimore
Cape May, N. J. 2.00--12   10       New York
Virginia Beach, Va. 2.00--12   28       New York
Fernandina, Fla. 2.00--12   50       New York
Key West, Fla. 2.00--12   65       New York
Sagaponack, N. Y. 2.25--13   10       New York
Sagaponack, N. Y. 2.25--13   24       Philadelphia
Sagaponack, N. Y. 2.25--13   36       Baltimore
Siasconset, Mass. 3.00--18   24       New York
Siasconset, Mass. 3.00--18   36       Philadelphia
Siasconset, Mass. 3.00--18   48       Baltimore
Camperdown, N. S. 4.00--24   36       New York
Camperdown, N. S. 4.00--24   48       Philadelphia
Camperdown, N. S. 4.00--24   60       Baltimore
South Wellfleet, Mass. 5.00--50   60       New York
South Wellfleet, Mass. 2.00--12   12       Boston

    Messages received from ships at the station will be delivered through land wires, the usual land toll being added.
    Those having accounts with the Wanamaker Stores may have incoming or outgoing messages charged if they desire.
    Incoming passengers from Europe may send orders to Wanamaker's via wireless, and we will care for them and, if desired, will have the goods at the ship on arrival.
    Visitors who may be interested are invited to see the new Wireless Station, which is situated on the Eleventh Floor. Guides may be procured from Visitors Headquarters in the Rendezvous, on the Eighth Floor, Central.