Disadvantages to Using an Underwater Telephone
Telephones Attached to a Network are all Stationary
Any type of network of underwater telephones connected to each other by cables would have to be stationary. This is a problem in a military setting, as it means that either side can knows where the submarine has to be to communicate with high command. This makes it a lot easier for the communicating submarine to be located, which is something submarines strive to avoid.
Limited Range
In calm seas, underwater telephones' range goes from approximately 2 miles to up to 7 miles. While this is decent, it serves only for local communication, nothing truly long range. For example, a maximum range of 7 miles is inadequate for communicating from the submarine to headquarter based on shore. Also, in rough seas, the ocean would get a lot noisier, which would reduce the effective range of the underwater telephone. This is the equivalent of cell phone coverage on land; if the telephone isn't close enough to one of the cell towers, it can't communicate. Similarly, if the submarine isn't close enough to one of the underwater telephones attached to the network, it can't use its telephone to communicate at all. Clearly, some other method of communication is required to receive or send orders if the submarine is not close enough to a underwater telephone.
Telephones are very Noisy
As mentioned in the overview, the underwater telephone works by transmitting pulses of sound through the water. Submarines' primary mission is often to just remain hidden, and any ship or submarine equipped with sonar in the area would easily detect the submarine that was using its underwater telephone.
Any type of network of underwater telephones connected to each other by cables would have to be stationary. This is a problem in a military setting, as it means that either side can knows where the submarine has to be to communicate with high command. This makes it a lot easier for the communicating submarine to be located, which is something submarines strive to avoid.
Limited Range
In calm seas, underwater telephones' range goes from approximately 2 miles to up to 7 miles. While this is decent, it serves only for local communication, nothing truly long range. For example, a maximum range of 7 miles is inadequate for communicating from the submarine to headquarter based on shore. Also, in rough seas, the ocean would get a lot noisier, which would reduce the effective range of the underwater telephone. This is the equivalent of cell phone coverage on land; if the telephone isn't close enough to one of the cell towers, it can't communicate. Similarly, if the submarine isn't close enough to one of the underwater telephones attached to the network, it can't use its telephone to communicate at all. Clearly, some other method of communication is required to receive or send orders if the submarine is not close enough to a underwater telephone.
Telephones are very Noisy
As mentioned in the overview, the underwater telephone works by transmitting pulses of sound through the water. Submarines' primary mission is often to just remain hidden, and any ship or submarine equipped with sonar in the area would easily detect the submarine that was using its underwater telephone.