Area Code 5991 – Carlow
The phone area code for Carlow is 5991 (international format +3535991). Browse local exchange codes (NXX) and carrier assignments below.
📞 Exchange Codes (NXX) for Area Code 5991
Select a central office code to view local carrier data and detailed information
📍 Geographic Location of Carlow
Geographic Overview
The +353 5991 prefix is a geographic National Destination Code (NDC) assigned to the Carlow area in the Republic of Ireland. Carlow is a county town in the South-East region, located approximately 80 km from Dublin. The code serves the town of Carlow and its surrounding areas, including parts of County Carlow and adjacent rural communities. It is administered under the national numbering plan by ComReg, the Irish communications regulator.
Dialing Formats
For callers within Ireland, the national format uses a leading zero: 05991 followed by the local subscriber number. For international callers, the format is +353 5991 followed by the local number. The full international dialing sequence is: +353 5991 XXX XXX (or +3535991XXXXXX when written as a continuous string). The local subscriber number typically consists of 5 to 6 digits, making the total number length (excluding the country code) 9 digits.
Caller Instructions
Local callers within Ireland should dial 05991 followed by the subscriber number. International callers should replace the leading zero with the +353 country code, so they dial +353 5991 followed by the subscriber number. For example, a local number 123456 would be dialed as 05991 123456 from within Ireland, and as +353 5991 123456 from abroad.
Geographic Coverage and Administration
The Carlow area code is part of the historic 059 area code region, which covers counties Carlow and Kilkenny. The 5991 prefix specifically identifies the Carlow exchange. As a geographic code, it is tied to the physical location of the line, and calls to this number are routed over the PSTN. The code is used for both fixed-line and, in some cases, VoIP services that are assigned geographic numbers.
Overlay and Numbering Considerations
Currently, there is no overlay code for the Carlow area; the 059 area code remains the sole geographic code for the region. However, number portability allows subscribers to retain their 05991 numbers when switching service providers, including mobile or VoIP operators, though the number remains associated with the Carlow geographic area. This means that a call to a 05991 number may be routed to a mobile or VoIP network if the subscriber has ported the number.
Practical Usage
Businesses and residents in Carlow use the 05991 prefix for local communication. For marketing and customer outreach, it is important to display the number in international format (+353 5991 ...) on websites and global directories to facilitate calls from abroad. When dialing from a mobile phone in Ireland, the same national format (05991 ...) applies, as the leading zero is required for all national calls.