The Universal Translator is a very handy gizmo that takes care of that annoying language barrier.
While Sues often cross this barrier with no problem, the agents are somewhat more handicapped, and often need to be equipped with these – especially any agent from a place where English is not the dominant language. PPC comms devices get a UT built in as a rule when DoSAT modifies them for cross-world communication, and agents are issued a separate UT regardless shortly after they are recruited.
Of course, they sort of take the fun out of swearing in foreign languages (though some Translators appear to be governed by the Laws of Narrative Comedy in this regard). They also translate written messages, so that written communication can be easily understood.
Some Universal Translators, like the ones employed by Agents Christianne and Eledhwen, have glitches where they translate one language, but not another. In their case, their Translator translates Westron, but not Sindarin. This has allowed Eledhwen to get away with speaking and cursing in Sindarin with her partner none the wiser (for the most part).
An organic version of the Universal Translator is the Babelfish, which originated in the Hitchhiker's Guide to the Galaxy continuum; the PPC generally prefers to use technology-based translators for ease of repair, but DoSAT does keep a tank of Babelfish to hand out to those agents who either cannot or are not allowed to use technology.
The Babelfish Virus (unrelated to the Babelfish) is not affected by the UT.
See Also: Fangirl Fanfiction Translator