I worked on telco OSS and billing systems at the beginning of my career. The industry benchmark is that 2/3 of all billing systems fail. Fail as in fail complet

I worked on telco OSS and billing systems at the beginning of my career. The industry benchmark is that 2/3 of all billing systems fail. Fail as in fail completely to deliver, not as in fail to deliver a 100% satisfactory result. A big part of this is legacy and marketers inability to discipline themselves and KISS, but legal and accounting rules also play their part. Never assume billing is going to be easy.