RADIOTELEPHONE CALL SIGNS

Call signs used in radiotelephone are commonly known as voice call signs. They consist of spoken words, which can be transmitted and understood more rapidly and more effectively than actual names of ships and afloat commands, or phonetic equivalents of international radio call signs. Under certain circumstances, however, the phonetically spelled international call sign is used in R/T for station identification. At other times, a ship's name serves as the call sign.

R/T call signs may be assigned by an operation order (OPORD), a tactical communication plan (COMMPLAN), or permanently by commonly held communications publications. R/T call signs may be either permanent or temporary, and they may be internationally usable or locally issued. In any event, call signs are used to identify the station and to establish communications. A station's call sign can be any of the following:

The name of the ship or aircraft tail number;

A voice call sign listed in Joint Voice Call Sign Book, JANAP 119;

An allied voice call sign listed in Tactical Call Sign Book (U), ACP 110; and/or

A call sign for ships listed in Call Sign Book for Ships, ACP 113.

Voice Communications, NTP 5, lists publications that contain encrypted and daily changing call signs.

A ship must use its call sign when first establishing a net or when reporting into a previously established net. After this initial contact, an abbreviated form of communications may be used.

If call sign encryption is in effect and a ship or unit name appears in the text, the name should be replaced by the encrypted call sign or address group of the ship or unit. When used in this manner, the call sign or address group may be preceded by the proword CALL SIGN or ADDRESS GROUP, as applicable.

ACP 113 CALL SIGNS

ACP 113 lists the international call signs and hull numbers for ships under military control. The call signs in this publication are unclassified. International call signs are used for all nonmilitary communications and military communications using unencrypted call signs.

JANAP 119 VOICE CALL SIGNS

Voice call signs contained in JANAP 119 are pronounceable words. They are for tactical use and are designed to facilitate speed on tactical radio circuits. Secure voice call signs can be achieved only by a conscientiously applied system for changing call signs on a frequent and periodic basis.

CALL SIGNS ON LOCAL HARBOR CIRCUITS

JANAP 119 does not assign voice call signs to administrative shore activities. Consequently, a ship cannot use a tactical call on administrative ship-shore circuits. When operating on ship-shore R/T circuits, a ship may use its international call sign. Operators must speak the call sign phonetically. For example, you would speak the international call sign NOKB as "November Oscar Kilo Bravo." The procedure described in the next paragraph may also be used.

In U.S. ports and U.S.-controlled ports overseas, the name of the ship serves as the voice call sign. As a rule, the USS prefix, hull designation and number, or the first name or initials of the ship need not be included in the voice call unless essential for clarity. This procedure also applies to shore activities on administrative nets. Each activity may use its administrative title in an abbreviated form, consistent with clarity. For example, Mobile Technical Unit 2 may have a voice call of MOTU on an administrative circuit.

Port authorities that control local harbor voice circuits are identified by the word "CONTROL." For example, let's say that the Key is entering port in New London, Conn. Key's initial call to New London Control to check into the local harbor net would be:

"Control, THIS IS Key, OVER."

If Key were to call Fuel Control, its call would be:

"Fuel Control, THIS IS Key, OVER."

You must remember that the simplified type of call is authorized only in U.S. ports or U. S.-controlled ports. If a ship is in a port not under U.S. control, it must conform to the international practice of using phoneticized international call signs on R/T circuits.

RADIOTELEPHONE CIRCUITS

Voice communications requirements are grouped into two basic categories: operational or tactical, and administrative.

OPERATIONAL OR TACTICAL CIRCUITS

Most voice circuits used at sea are operational or tactical nets; some circuits, however, are often used to pass administrative traffic. These circuits are subcategorized into two distinct types: short and long range.

Short-range operational communications normally use the UHF frequency spectrum (225 to 400 MHz) and low-power, line-of-sight equipment. Because of these frequency and equipment characteristics, the maximum effective range is usually 20 to 25 miles. This limited UHF range offers no security, and transmissions are always subject to enemy interception. However, since these transmissions are limited somewhat to the local geographic area, interception by an enemy would be difficult. On the other hand, the range of UHF communications may be extended through the proper use of relay procedures.

More and more, our modern and high-speed ships must report to OTCs from longer distances than the older ships they replaced. Long-range frequencies in the medium- and high-frequency spectrum (2 to 32 MHz) are, therefore, used. From your study of module 4, you will remember that the propagation characteristics of these frequencies make them desirable for long-range communications. To further increase the range capabilities of long-range communications, we use single-sideband (SSB) methods.

ADMINISTRATIVE CIRCUITS

Administrative circuits are normally used only in port and may include both short- and long-range communications. Voice circuits that are neither operational nor tactical are included in the administrative category. Seldom is there such a circuit in at-sea communication plans.

Harbor common circuits and tug control nets are two examples of administrative nets. Naturally, these nets assume an operational function during situations requiring emergency procedures, such as natural disasters and civil uprisings. Circuit requirements vary from port to port, as established by the senior officer present afloat (SOPA). Both the UHF and MF/HF circuits may be used for administrative nets.