What is the area code of Phillips county in Montana?
"PHILLIPS" is the county; 'Montana' is the name of state
SELECT DISTINCT T1.area_code FROM area_code AS T1 INNER JOIN country AS T2 ON T1.zip_code = T2.zip_code INNER JOIN state AS T3 ON T2.state = T3.abbreviation WHERE T2.county = 'PHILLIPS' AND T3.name = 'Montana'