MIB is a “bankers’ bank” which provides a wide array of correspondent banking
services to close to 525 financial institutions throughout the Midwest. Based in
Jefferson City, MIB’s banking services are provided exclusively to financial
institutions.
My local bank is contracted with MIB for international transfers as they don't have their own swift number; I called to inquire about the status of an incoming wire from Germany that had not been returned or forwarded for 3 weeks and neither the sending bank nor the receiving bank could help me with. The guy I got on the phone was extremely rude and unwilling to provide any assistance to anyone but a banker. I asked him if he could at least give my bank a call to resolve this and he said he would. He did not, however my $3k did get returned shortly thereafter.
If your bank asks you to direct international transfers through MIB consider using PayPal or Western Union instead.