It's the main line to the university hospital in Denver - many large places like that have the same 6 first numbers and the main line to the operator ends in 0000, then the rooms and doc's all have the last 4 numbers are different, in the springs it's also the end to the main number to police and again the subdivisions and other people with office's have their extention you can be transferred to know or just replace the 0's with the 4 digit extention and dial direct.... It also frequently corresponds to the room number in some places.