as for landline subsitutes, my friend uses Vonage.. I have to tell you, that I really do not like speaking to him on that darn thing...
the main problem? His phone does not allow for overlapping conversation, so you almost have to do the old walkie-talkie thing and say “over” when you finish saying something. That is terrible in my opinion.
on land lines, you can have a real conversation, that has overlapping in it...
Sounds like a bandwidth problem. In the nine years I’ve been using it, the only time I had difficulty was the 18 months I spent in an apartment with bad internet.
Even then the problem wasn’t lack of overlap. Just an occasional garbling.