The calls routed to Customer Service are inquiries related to payment applications, principal curtailments, tax and insurance disbursements, escrow analysis, assumption, adjustable rate mortgages, payoff statements, and all other inquiries regarding current mortgage loans. BOK Financial, Headquartered in Tulsa, Oklahoma, BOK Financial Corporation (NASDAQ: BOKF) is a top U.S.-based financial services holding company with operations in Oklahoma, Texas, Arizona, Arkansas, Colorado, Kansas, Missouri, Tennessee and New Mexico.