Sticky Sender
What is Sticky Sender?
A sticky sender is a number-pooling strategy that maps a given recipient to the same sending number every time, instead of picking a different number from the pool on each send. The first message to a new recipient picks a sender deterministically, and that pairing is then remembered, so a reply thread — support, two-way SMS, appointment reminders — always looks like it is coming from one consistent number instead of a different one each time.
More detail
Sticky sender is a selection strategy within a sender pool, not a separate pooling mechanism — the same pool can run sticky, round-robin, random, or geo-matched selection depending on the traffic it carries.
Consistency matters for deliverability as well as recipient trust: carriers and recipients both treat a stable number as more legitimate than one that changes on every message, and a recipient who saved or replied to a number expects follow-ups to keep arriving from it.
Orbit's sender pools default new pools to a sticky strategy for this reason, falling back to sticky whenever a geo-matched pool has no local sender available for a recipient's country, rather than failing the send or breaking the pairing.
Frequently asked
- What is a sticky sender in SMS or messaging?
- A sticky sender is a number-pooling rule that always sends to a given recipient from the same number in the pool, so a reply thread stays on one consistent sender instead of switching numbers between messages.
- How is sticky sender different from number pooling?
- Number pooling is the broader practice of sending from a shared set of numbers instead of one; sticky is a specific selection strategy within a pool that keeps each recipient pinned to the same number, as opposed to round-robin or random strategies that intentionally rotate.
- Does a sticky sender assignment ever change?
- It can, if the assigned number is removed from the pool or its deliverability degrades — the pool then deterministically picks a new sender for that recipient and remembers the new pairing going forward.
See also
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