How do i find my routing number for first interstate bank? Please call (406) 237-2951 to verify routing number for your bank wire transfer, reorder First Interstate Bank checks or setting up direct deposit. You can also get your First Interstate Bank routing number on your check, view sample check to locate your ABA number.Where is the corporate headquarters of first interstate bank? First Interstate Bank has 163 banking locations. Their corporate headquarters is listed as: 401 North 31st Street in Billings Montana. Below you will find ratings, reviews, corporate information, directions, office hours, their phone number, online banking website, and branch locations.How does first interstate bank communicate with me by email? First Interstate Bank has partnered with Mimecast to communicate securely with you by email. Secure mail transmits encrypted messages that only authorized recipients can access.How many first interstate locations are there? With over 150 locations across Idaho, Montana, Oregon, South Dakota, Washington, and Wyoming, First Interstate is still run on the same principles as when it was founded by Homer Scott, Sr. in Sheridan, Wyoming in 1968 – to take the best possible care of our customers, our employees, and the places we call home.