How it works
From a CTECC dispatch to a Briefing on your phone.
Six steps. Total median latency around three minutes — every step measured by the synthetic monitoring probe that runs every fifteen minutes, day and night.
01
Dispatch happens
CTECC, the consolidated dispatch center for Austin Fire Department and all 14 Travis County ESDs, dispatches units to a fire. The event is written to the City of Austin's public Real-Time Fire Incidents dataset within seconds.
Source: City of Austin Open Data — wpu4-x69d
02
FireSignal ingests
A cron poller hits the Open Data API every five minutes. New rows since the last poll are deduplicated against the active incidents table by traffic report ID. No scanner audio, ever — the federal commercial-use ambiguity around scanner-derived data isn't a fight we want to pick.
5-minute polling interval · idempotent ingest
03
Geocode + parcel match
The Open Data feed provides lat/lng, but we re-geocode the address through Mapbox to backfill any gaps. PostGIS then runs a point-in-polygon match against the TCAD parcel layer — that's how the Briefing knows which property the truck is being sent to.
374,461 Travis County parcels indexed · 95.5% geometry coverage
04
Territory routing
Each subscriber draws their service area inside the county. The routing engine intersects the dispatch location against every active territory, applying severity gates and quiet-hours rules. Synthetic test incidents are filtered out by four independent guards before this stage.
PostGIS ST_Contains · severity + confidence gates · quiet-hours honored
05
SMS goes out
A single-segment 160-char SMS lands on the contractor's phone via Twilio. The body is GSM-7 safe (no em-dash, no emoji) so it never gets fragmented across messages. A per-incident 4-character code identifies the briefing — short enough to type, long enough to be unguessable.
Single segment · GSM-7 · per-incident code
06
Briefing loads in <1s
Tapping the link opens The Briefing — a mobile-first page with the address, severity badge, unit roster, satellite tile, TCAD profile, and a sticky Mark Responding action. No login. Possession of the SMS link is the auth. Realtime updates flow in as CAD changes propagate.
Mobile-first · server-rendered · realtime via Supabase
What lands on the phone
Two surfaces: the alert and the Briefing.
FireSignal · iMessage / SMS
FIRE 78751 4413 Avenue G 6 units, 2 min ago getfiresignal.com/i/9k4r Reply Y 9k4r = resp / STOP
Delivered · 108 chars · single segment
Exact 108-char alert body, GSM-7, single segment.
Austin Open Data · refreshed 2m ago
4413 Avenue G
STANDARDRESIDENTIAL FIRE
Dispatched 3 min ago · zip 78751
Property profile
- Year built
- 1948
- Square feet
- 1,620
- Appraised value
- $612,500
- Property class
- Residential - Single Family
Dispatched 22:14:08 → Alert sent 22:15:51 (1m 43s elapsed)
The Briefing — opens in < 1s, no login required.