The Royal Navy used what it called Wireless Telegraphy (W/T) to communicate between ships and the shore; this was radio, but using morse code rather than voice signals. It used four main frequency bands. Very Low Frequency (VLF), with frequencies below 30 KHz, was used to communicate with submerged submarines, as these were the only frequencies capable of passing through water. At the start of the war, Low Frequency (LF, frequencies between 30 and 300 KHz) was most prominent. This was a relatively short-ranged system, and was well-suited for communications between ships and nearby shore bases. This suited the RN well, as it was planning to fight actions close to its bases, or to establish forward bases and fight near them. Medium Frequency (MF, 300-3000 KHz) was also used at this time, but was rarer compared to LF systems. Finally, High Frequency (HF, 3000-30,000 KHz) began to dominate as the war progressed. HF was the only long-range system, as its waves could bounce off the ionosphere/Heaviside Layer, and as such, was not limited by the horizon. As RN ships began to operate further from their bases, the use of HF radios was forced. VHF radios were also used; with a frequency higher than 30,000 KHz, they were limited to line-of-sight. They were typically used for communicating with nearby aircraft, or for communication within a fleet. These were typically radio telephony systems (R/T), which allowed for voice transmissions.

The RN could make use of the extensive British Empire to establish a wide range of transmitting stations, from which communications could be sent to ships at sea. They divided the world up into 21 Sea Zones. Each of these had one main transmitting station, with fall-backs and other options. For example, Malta was the main transmitting station for the Mediterranean, the Falklands for the South-West Atlantic, and Colombo for the Indian Ocean. Each of these stations made what was called the 'Area Broadcast', a stream of messages which contained Admiralty instructions and intelligence, and which all ships in the area listened in to. Ships might also listen to broadcasts from other areas; it was common for flagships to keep an eye on the broadcasts from adjacent areas. Messages could be sent to particular ships as well, and replies were also received at these stations.