For business purposes, I have an Asterisk PBX set up in my home office. It uses SIP trunks and I can administer it remotely over the web (with a dynamic DNS config). My issue is this: I use an xLite softphone app on my laptop; it work fine almost everywhere I have Internet access except when I connect via my Verizon hotspot. This is a serious issue for me as it is impacting my business. I know it's not the softphone config since it connects as soon as I connect on another network (typically, in a client's office). The main reason for even getting the hotspot was to deal with locations where I might not have Internet access. My own thoughts on this is that Verizon blocks SIP apps, but I haven't found that explicitly yet.
So, I found myself in the ridiculous position of spending money to lose business.