If you've ever been a substitute for multiple districts you've likely had a chance to become familiar with multiple substitute placement systems. Each one has it's pros and cons but the inner workings of the system are relatively unknown to most substitutes. Only school staff and administrators are privy to the specific settings of each system. After many years of working a substitute and actually going through a transition between two different placement systems, I have discovered some of the cool (and not-so-cool) features of the top three frequently used absence management systems.
SubFinder is your average, middle of the road sub placement system and, until recent years, was the most popular. It is a fully automated system that places calls based on the particular settings of a school district. Typically, the system runs down a list of subs in alphabetical order but the changes to the settings can create a different priority ranking. For example, recent layoffs have required school districts to give priority to their pink-slipped teachers so they adjust settings to make calls to them first; then come the fully credentialed substitutes and finally the emergency credentialed subs. SubFinder also keeps a history of each job, how many calls were made, who turned it down, and who accepted. I don't think this is used to determine who's more likely to take the job but more of a liability issue in the case that a substitute applies for unemployment insurance. Although SubFinder is an automated system, it still needs a live person at the helm. What I've noticed is that an administrator is used in conjunction with the system and they often override system preferences by manually placing calls to substitutes. SubFinder is most useful afterhours when the admin has gone home.
Smaller districts may still have a live person in house making calls. This can be a complicated and arduous process depending on who's doing the job. In one district where I've worked, a single person was assigned to this position and she worked from 5 AM to 9 PM checking voicemails and calling substitutes. She had created her own complex tracking system noting who she had called, how many times they were unavailable, their distance from the schools, grade preferences, etc. All of this information was kept in a handy binder that she took home with her at 2:30 where she continued working until 9 PM. Instead of an automated system, there was a district voicemail where teachers left their absences. The admin would check every half hour for any calls and then contact subs. Likewise, subs had to call in and report unavailability on the same voicemail. It feels almost like you're turning down work before you've even got it. This system is messy at best and has numerous drawbacks. The admin calls at her discretion and, if you are called for another district at 5 am, she may not know you're in the classroom and she'll call you mid-lesson causing you miss a potential day of work. In some districts, the admin is typically not as dedicated and they stop making calls at the end of their workday until the are back in the office at 6am the next day. This can mean many unfilled absences. The only benefit of this system is being able to form a personal relationship with the admin. If you consistently fill absences you can get into an admins good graces and they may break the rules to give you more work.
Probably my favorite system although from what I've read, subs either love it or hate it. I feel that this system is more user friendly since it has to be handled by teachers, staff, and substitutes. It's also one of the few systems that can single-handedly eliminate the need for a live admin, taking away the guilt of turning down assignments. When the district I work for switched from SubFinder to AESOP the live admin "retired" and I never heard a human voice again. The AESOP system has many customizable functions for all who use it and allows teachers to make a list of preferred subs as well as blocking those they dislike. This combined with the rating/comment system gives some much deserved recognition to substitutes that deliver. I feel that those that can't stand this system probably don't, which is why they get no work. There may also be another function where a job is automatically assigned to a substitute but this is not standard practice in all districts. Similarly, substitutes can pre-designate days they can't work and rate a teacher's lesson plans. I love this feature because, as all subs know, some lesson plans are poorly prepared. You can also see all your jobs at a glance on the calendar. But a word of caution, sometimes if you drop an assignment you will automatically be blocked from receiving another assignment on that day. Typically, the system will warn you of this but I think it is dependent on the settings of the district.