Well, weapons/rockets/space etc. is another story. This sector was intensively supported, the best scientists and developers worked there, so it was OK.
Anyway, looking at 80s, you may found that the most Soviet complicated electronics sold in shops were either good but a sort of monster things (design, size etc.) or just copies of foreign models (yeah, step-by-step taken copies, such as some Soviet VCRs, audio cassette recorders etc.). It's known there were Soviet i8086 and i80286 clones, but they had stuck with i80386.
So, seriously, I guess they would be able to construct their own Soviet GSM phone, but it would be not that convenient to use and it would contain many copied content (from cloned chips upto firmware). :P Nevertheless, this had no chance to happen, although I've heard Ukrainians (may be Belorussians, I'm not sure) recently made their own GSM phone from start to end, which is way too big, looking as a phone from late 90s. :whistle: Well, what a funny topic.
Do you know something specific about the North Korean GSM network? It looks to be very weird. It has no roaming agreements and I'm afraid there are just a few BTS covering the places where their leader used to be.
Cuba is not such a close country with more relaxed life and it's visited by many foreign tourists, so fully functional GSM network is quite needed there, and it does exist. I find it expectable.
I guess Transdnistria people can use both Moldovan and Ukrainian coverage, but it seems to be reasonable only for innernetwork calls, while calls to Transdnistria landlines are probably expensive. Anyway, Transdnistria is not blocked from outside, so it's not a problem to get scratch cards and so on. I'll look for more real info on that topic, since it's quite interesting.
I guess Russian telecommunication law contains the same stuff (sort of partial state tariff regulation) only for landline monopolists, which keep 90% or more of landlines under their control, it's the same as in Poland. Now here are usually 3 or more cellular operators sharing the market equally, but they didn't have to make any discounts for anybody when they were alone in a region (in 90s, for example).