What is the JMP.chat bus-factor?
Right now it is 3: ossguy and singpolyma and psycotica0
How can users recover their numbers should JMP.chat disappear?
The numbers are held by Bandwidth but that's not all that important. Users can recover their number by contracting with a new carrier and asking them to port their number, the new carrier then contacts whomever holds the number to perform the transfer (i.e. no need to talk to Bandwidth at all).
The JMP.chat account at Bandwidth "fails open" - that is to say, users can port your number away with no restrictions if JMP.chat goes away.
NB: it is possible to set a port-out PIN via support.
Where are the JMP.chat servers located?
OVH data centre in Beauharnois, Quebec (just south of Montreal)