Better yet, don't use an explanation at all!

If you establish something as just being part of your setting that is accepted by the characters in it like it's no big deal, you can just move on with the actual plot. If it's not actually going to be relevant to anything plot wise, don't waste time with useless technobabble!

Slap a "Zephyr FTL Communications" logo on the side of the terminal and call it a day. The audience doesn't always need to know how, just what. And show, don't tell.

You can have a character exposition dump about a piece of tech that should be as normal to the other characters as a telephone (so why would anyone talk about it existing casually outside of very specific circumstances), or just... have the character use the damn thing and add a little splash screen on the device "Thank you for using Cisco Intergalactic FTL calls".