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Selfhostsms

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Reaching people who have no smartphone, no data and no app

The need

Product decisions are often made on the assumption that everyone carries a smartphone with a working data plan. For a great many customers, that assumption is wrong: a feature phone, a prepaid line with no data left, a village with two bars of 2G, an elderly customer who will never install anything.

For those people an SMS is not a degraded notification. It is the only one that arrives.

The setup

  1. No install, no account. The message reaches the number. There is nothing for the recipient to accept, download or log into, which removes the step that loses most of an audience.
  2. Your own SIM cards, on the local network. Sending from a line of the same carrier as your customers is the shortest route there is, and the one least likely to be filtered as foreign traffic.
  3. A directory that survives. Contacts, groups and tags live in your own database, exportable whenever you want. A list built over years does not belong in a service you rent.
  4. A reply that is read. People answer SMS. The inbox catches those replies instead of dropping them, which turns a notice into a conversation.
  5. Opt-out that works by itself. A reply of STOP unsubscribes the number, whatever the accent or the punctuation, and the unsubscription is held by number rather than by contact: deleting the contact does not undo it.

What to watch

The alphabet costs money. A single accented character switches the whole message to a coding that holds 70 characters instead of 160. The segment counter shows it while you type, which is the moment it can still be changed.

One SIM has a rhythm. A line that sends hundreds of messages in a few minutes looks like spam to the carrier, and carriers suspend before they ask. Per-SIM quotas and a minimum interval between sends exist for that, and a campaign spreads across the phones you have.

Think about when the phone is charging. The gateway runs on phones you own, and a phone that stays on its charger is a phone the system never puts to sleep. It is the single most effective thing you can do for reliability, and it costs nothing.