I found it incredibly terrible to have no reliable Internet in times of remote work, and doing technical sales over VOIP, or video.
Stuttering, bad microphones on 9 out of 10 consumer gear having them, laggy/blurry web cameras, and the biggest one, packet loss, completely annihilate that image of confidence that a technical salesman should irradiate.
Having video calls, especially to 3rd world countries gradually turn to schmoo as you go into deal details, having to switch to audio only, which then automatically turns off the loudspeaker, and long field microphone, only to have to switch to a POTS, and realise it's suffering the same issue due to it coming over internet in the country is an ultimately frustrating experience for both you, and the prospective client.
On the opposite end, having an extra premium experience of shining HD image, and loud crystal clear voice helps you to project your image. I believe this alone can give you 20%-30% extra chance to bring the client on your side.
Purposeful VOIP packet shaping is the ultimate evil.
Telephone and video conferencing today is unreliable because there are many parts that can break. You might have an absolutely great internet connection but your client could have a bad connection (if only on that they day) or problems with their audio, etc.
I knew a recruiter who worked in LA in the early 2010's somewhere around the intersection of the 405 and 101 north of the Santa Monica Mountains. This was near the peak of the 3G era where cell networks couldn't really handle high urban density in the U.S.
He was having bad connections, calls dropping, etc. He was still placing people though.
People have a lot of forbearance for broken comms today because it is widespread but as someone who is basically introverted I find it especially tiring to be on calls where I have to struggle what the other party is saying.