Subspace communication number
A subspace communication number, communications number, or subspace number was a numerical sequence that designated a particular subspace channel.

In 2381, the  conducted a second contact mission to have the Apergosian High Leader choose a subspace communication number. When he kept dithering, Commander Jack Ransom pointed out that the number did not really matter as a computer could automatically route transmissions to the correct recipient. Nevertheless, the High Leader insisted that he needed a number with suitable "gravitas". ()

See also 
 Phone number
Communications technology