Buying a phone number is a distributed transaction

The API makes it look trivial. const number = await carrier . numbers . buy ({ phone_number : " +1... " }); await db . insert ( " rented_numbers " , { user_id , e164 : number . phone_number }); await stripe . subscriptions . create ({ customer , price }); Three lines, one number, done. Ship it. What you actually wrote is a distributed transaction across three systems. They share no transaction log, they have no two-phase commit, and none of them can roll back the others. The carrier will keep charging you for a number your database has never heard of. Stripe will stop charging for a number your database still thinks is paid up. Neither one is going to mention it. I run a virtual phone number product. Below are the failure modes that actually cost us money, roughly in order of how much. The orphan taxonomy Write down the states first, because the interesting ones are the states nobody designs for. Three systems, each holding an opinion about a single number: Your DB Carrier Stripe What is actually happening active owns it active The happy path. Rare in the tail. no row owns it nothing You pay monthly rent on a number nobody can see or use. active released active You bill a customer for a number you no longer own. pending_cancellation owns it canceled Customer stopped paying. You are still paying the carrier. active owns it canceled You provide service for free, indefinitely. cancelled owns it canceled Release failed at teardown. Silent monthly bleed. Every row under the first one is reachable from a plain network timeout at a bad moment. The first orphan class is the worst, because you cannot see it from inside your own product. No row, no user, no support ticket. The number sits in the carrier's inventory producing an invoice line every month until somebody actually reads the invoice. The second class is the one that generates a complaint. The rest leak money in one direction or the other, quietly. Reconcile, don't prevent The instinct is to armour the write path. S