Hey, mrpink. I don't know what audio produciton capabilities you have, but even if you don't have access to anything that can run a plugin, you can easily get in the ballpark by just rolling off the high and low freqs with some eq and adding some 'orrible sounding distortion/clipping to whatever midrange you have left. You'll need to fiddle a bit to get it to get it where you want it, but it's probabaly one of the easier effects to dial in manually.
There is a lot of difference between a typical TV sound and a walkie talkie though (you'll need to crank up the clipping more, and raise the low eq cutoff more on the latter). Make sure to use some professionally produced reference sound examples to check yours against.
Afterwards you can then drop in some ambience and reverb to tie it into the visual environment as per any other sound.