Local Calling Guide

Rate centre information

Search by rate centre (exchange) name, region, area code, LATA. Enter full or partial name. Use official postal abbreviations for province/state/territory.

Keystone, SD [Prefix detail]

LATA: 640 SOUTH DAKOTA

LIR:

V: 06567 H: 05920

ILEC: 1660 FORT RANDALL TELCO DBA MT RUSHMORE TELEPHONE CO

Includes all or part of:

NPA 605:

666

See all [Local Prefixes]

Local calling FROM 3 exchanges: [Reverse direction]

Rate centrePlan typeCall typeMonthly limit (minutes)NoteEffective date
Hermosa, SD     
Hill City, SD     
Rapid City, SD     

Last updated: Thu, 05 Feb 2026 23:41:55 UTC

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