Another aspect is that audio quality of GSM calls is just awful. Especially when calling any business, it sounds like it's been converted between 8KHz PCM and

Another aspect is that audio quality of GSM calls is just awful. Especially when calling any business, it sounds like it's been converted between 8KHz PCM and 32kbps MP3 back and forth a dozen times, with a second-long lag. I can't understand what anyone is saying, they can't hear me, and the whole ordeal is mentally draining.