140.15

140.15 is the frequency used by a number of characters in the Metal Gear series. Meryl Silverburg used the Codec frequency to communicate with Solid Snake during the Shadow Moses incident.

Background
In Metal Gear Solid, the discovery of this frequency is unique in that it was not revealed in-game; rather, in a case of breaking the fourth wall, the frequency appeared printed in the back of the game case in both versions. Canonically, the character Kenneth Baker intends to give Snake the frequency, but has forgotten it; he informs Snake the "it should be on the back of the CD case" (in The Twin Snakes, a slightly more cryptic "back of the package" is used instead).

This minor twist would become infamous among players who had rented the game; since many video game rental outlets such as Blockbuster do not provide the original packaging along with the game, the only option for these players was to use an online guide to discover the frequency. At the same time, however, it was vital to show to players early in the game that MGS was a very different gaming experience than they were used to.