There's no rule:
7226780912
Fast spelling: setecientos veintidós, seiscientos setenta y ocho, cero, nueve, doce / setenta y dos veintiséis, setenta y ocho, cero, nueve, doce
Less frequent: siete, dos, dos, seis, siete, ocho, cero, nueve, uno, dos.
depends what the number is for...phone, math, ..etc
el numero de telefono de mi madre
Telefono
The phone number of the Spanish Fork Public Library is: 801-798-5010.
The phone number of the Spanish Springs Library is: 775-424-1840.
Google translator states it as "número de teléfono"
The phone number of the Spanish River Library is: 561-393-7852.
The phone number of the Historic Spanish Point is: 941-966-5214.
The phone number of the Colonial Spanish Quarter And Spanish Quarter Museum is: 904-342-2857.
The phone number of the Spanish Governor'S Palace is: 210-224-0601.
The phone number of the Spanish Peaks Library District is: 719-738-2774.
The phone number of the Old Spanish Fort Museum is: 228-769-1505.