Area Code 5791 – Birr
The phone area code for Birr is 5791 (international format +3535791). Browse local exchange codes (NXX) and carrier assignments below.
📞 Exchange Codes (NXX) for Area Code 5791
Select a central office code to view local carrier data and detailed information
📍 Geographic Location of Birr
Geographic Overview
The +353 5791 prefix is a geographic National Destination Code (NDC) assigned to the town of Birr and its surrounding areas in County Offaly, Ireland. This code falls within the larger 0579 area code group, which serves the midland region of Ireland. Birr is a historic market town known for its Georgian architecture and the famous Birr Castle Demesne, home to the Leviathan telescope. The town is located in the province of Leinster, approximately 120 km west of Dublin.
Dialing Formats
When calling a Birr number from within Ireland, you must use the national trunk prefix 0 followed by the area code and the subscriber number. For example, a local Birr number might be dialed as 057 91 12345 (where 12345 is the local 5-digit subscriber number). Note that the area code is 057 and the prefix 91 is the first part of the local number, but in international format, the entire NDC is 5791.
From outside Ireland, you would dial your country's international access code (e.g., 00 or +), then 353 (the country code for Ireland), followed by 5791 and the subscriber number, omitting the leading zero. For instance, to call the same number from the United States, you would dial 011 353 5791 12345.
Local vs. International Calls
For local callers within the Birr area, it is possible to use short dialing (without the area code) if the call is within the same local exchange area. However, for calls from other parts of Ireland, the full national format 057 91 12345 is required. International callers must always use the +353 5791 format.
Overlay and Numbering Plan Considerations
Ireland's numbering plan is regulated by ComReg. The 0579 area code group is not subject to overlay codes; it is a standard geographic code. The number length for geographic numbers in Ireland is typically 7 to 8 digits for the subscriber number, but in this case, the subscriber number after the NDC is 5 digits, making the total national significant number (NSN) length 9 digits (including the leading 0). This is consistent with the ITU-T E.164 recommendation.
When dialing from a mobile phone, the same rules apply as from a fixed line. However, mobile users should be aware that calls to geographic numbers are typically included in their call allowances or billed at standard rates.
For businesses in Birr, having a geographic number can enhance local trust and presence. It is also possible to use VoIP services to obtain a Birr number, allowing businesses to have a local presence without a physical office.