Cambodian phone
Which network, whether it is valid, and every format you need it in.
One number, six ways of writing it
012 345 678. 012345678. +855 12 345 678. 85512345678. 0855 12 345 678. Every one of those is the same phone, and a form that accepts all of them and stores whichever arrived is a contact list nobody can dial from and a WhatsApp link that silently fails.
The fix is to accept anything and store one shape. This page shows you which shape, and what the number you have actually is.
The mistake almost everybody makes
Writing +855 012 345 678 — the country code and the leading zero together. The zero is the domestic trunk prefix; it exists so a caller inside Cambodia knows the next digits are an area or network code. Once the country code is there, the zero must go.
Kept together, the number is one digit too long. Some systems quietly drop it, some fail, and the ones that fail do so at the worst moment — a delivery driver trying to call, or an automated message that never arrives.
What the prefix tells you
The first three digits say which network issued the number: Cellcard, Smart, Metfone, qb or Seatel — or, for a landline, which province. That is genuinely useful for knowing which app someone is likely to be reachable on, and for spotting a typo in the first three digits, which is where typos hide.
It says who issued it, not necessarily who carries it today. It is also worth checking against the regulator once a year, because allocations do change as networks are granted new ranges.
Store it as +855
E.164 — a plus, the country code, and the national number without its leading zero, no spaces — is the one form that works for dialling, for WhatsApp, for SMS gateways, and for matching two records that were typed by two different people.
Display it however reads best for the audience: the local form on a Cambodian page, the international form on a business card. Format on the way out, never on the way in.