Oh hilarious! The business logic for getting optimal routing for faxes was... quirky. Picking the right source country/line/carrier to get the best quality line while getting the lowest cost and balancing capacity. In the old days all held in a complex queue in a MySQL db (sigh). I recall getting paged out of bed a number of times as an escalation to get it all working again after we hit yet another lock contention issue in MySQL.

Good times!