Sec. 90.735  Station identification.

    (a) Except for nationwide systems authorized in the 220-222 MHz 
band, station identification is required pursuant to Sec. 90..425 of 
this part.

[[Page 589]]

    (b) Trunked systems shall employ an automatic device to transmit the 
call sign of the base station at 30 minute intervals. The identification 
shall be made on the lowest frequency in the base station trunked group 
assigned to the licensee. If this frequency is in use at the time 
identification is required, the identification may be made at the 
termination of the communication in progress on this frequency.
    (c) Station identification may be by voice or International Morse 
Code. If the call sign is transmitted in International Morse Code, it 
must be at a rate of between 15 to 20 words per minute, and by means of 
tone modulation of the transmitter, with the tone frequency being 
between 800 and 1000 hertz.
    (d) Digital transmissions may also be identified by digital 
transmission of the station call sign. A licensee that identifies its 
station in this manner must provide the Commission, upon its request, 
information (such as digital codes and algorithms) sufficient to 
decipher the data transmission to ascertain the call sign transmitted.
[ 56 FR 19603 , Apr. 29, 1991, as amended at  62 FR 15997 , Apr. 3, 1997]