Area Code Lookup
What Area Code Is Sidney?
3 area codes serve Sidney
Sidney is served by area codes 406, 431, 447. It spans Montana and Manitoba and Illinois.
Area Codes Serving Sidney
Frequently Asked Questions
What area code is Sidney?
Sidney is served by area codes 406, 431, 447.
Why does Sidney have multiple area codes?
As demand for phone numbers increased, NANPA added area codes through splits (dividing the region) or overlays (layering a new code over the same geography). Sidney now has 3 area codes — 406 and 431 and 447 — covering the same or overlapping areas.
How do I call Sidney from outside the US?
To call Sidney from abroad, dial +1 followed by the area code and 7-digit local number (e.g. +1-406-XXX-XXXX). The +1 is the country code for all NANPA countries.