That's a fair reluctance and I can't take it away because at the end of the day you'll just have that lock-in with anyone. Such is the nature of telco lines. I have the same problem (having carried my home phone line through multiple stacks).

What I can say is that I can cover costs out of pocket every month indefinitely (because each user covers their telco costs of that line, I'm just covering infrastructure) and my hosting fees are easy to cover even if we have no users.

We're probably not a typical startup in that sense. We have sustainability and independence in mind. At this point the only thing investors could offer us is the ability to grow faster. An important thing, but I like giving stability its own rights, too.