Area Code 423 – Dundalk/Carrickmacross/Castleblaney
The phone area code for Dundalk/Carrickmacross/Castleblaney is 423 (international format +353423). Browse local exchange codes (NXX) and carrier assignments below.
📞 Exchange Codes (NXX) for Area Code 423
Select a central office code to view local carrier data and detailed information
📍 Geographic Location of Dundalk/Carrickmacross/Castleblaney
Geographic Coverage and Administration
The +353 423 area code is a geographic National Destination Code (NDC) assigned to the north-eastern region of the Republic of Ireland, primarily serving the town of Dundalk in County Louth, along with Carrickmacross and Castleblaney in County Monaghan. This code is administered under the national numbering plan overseen by ComReg, the Commission for Communications Regulation. The region is part of the Border, Midland and Western (BMW) area, with Dundalk being the largest town and a key commercial hub near the border with Northern Ireland.
Dialing Formats and Usage
Within Ireland, calls to numbers in the 423 area code are dialed using the national format: 0423 XXX XXX (or 0423 XXXXXX, depending on the subscriber number length). The leading '0' is the trunk prefix used for domestic calls. For international callers, the format is +353 423 XXX XXX, omitting the trunk prefix. The 423 code is part of the larger 042 area code region, which was historically a single code (042) covering Dundalk and surrounding areas. In 2013, ComReg introduced a new numbering scheme that split the 042 region into multiple area codes, including 423, to accommodate the growing demand for numbers. This change required all local calls to include the full area code, even for calls within the same town.
Caller Instructions
- Local callers (within Ireland): Always dial the full national number, including the leading '0' and the area code. For example, to reach a Dundalk landline, dial 0423 123 456.
- International callers: Dial your country's exit code (e.g., 011 from the US/Canada), then Ireland's country code +353, followed by the area code without the leading '0', and the subscriber number. For example, from the US, dial 011 353 423 123 456.
- Mobile and VoIP users: When calling from a mobile phone, you can typically use the international format with a '+' sign: +353 423 123 456.
It is important to note that the 423 code is strictly geographic and tied to the physical location of the fixed line. Calls to these numbers are generally charged at standard national rates for domestic callers, while international rates apply for calls from abroad. There are no overlay codes in this area, meaning the 423 code is unique to this region. Businesses and residents in the area often use these numbers for local presence, and the code is not portable outside the geographic region, as per ComReg regulations.