Monaghan is in Irish area code 047, which is +353 47 in international format.
(The plus sign means "insert your international access prefix here." From a GSM mobile phone, you can enter the number in full international format, starting with the plus sign. The most common prefix is 00, but North America (USA, Canada, etc.) uses 011, Japan uses 010, Australia uses 0011, and many other countries use different prefixes.)
Kilcar in County Donegal, Ireland, is in area code 074, which is +353 74 in international format.
0035321 + the local number
The telephone area code for Dunshaughlin in County Meath, Ireland, is 01. This code is part of the Dublin metropolitan area, and it covers various towns and suburbs in the region. When dialing from outside Ireland, you would need to use the country code +353 followed by the area code and the local number.
The telephone area code for Ashbourne, County Meath, Ireland, is 01. This code is used for landline numbers in the Dublin region, which includes Ashbourne. When dialing from outside Ireland, it is necessary to include the country code +353 and drop the leading zero, so it would be +353 1 for calls to Ashbourne.
Rowley Regis is in area code 0121, the same as Birmingham. To call from Ireland, dial: 00 = international access prefix from Ireland 44 = country code for UK 121 = UK area code, dropping the leading 0 (7-digit subscriber number)
Essex has several different telephone area codes. To call the UK from the Republic of Ireland, replace the leading 0 of the UK domestic number with 00 44.
There is no telephone area code 185 in Russia.
003531
Country code +35 is assigned to Ireland.
The country code and area code of Letterkenny, Ireland is 353, (0)74.
The country code and area code of Carlow, Ireland is 353, (0)59.
In July 2015 the first postal code system, known as Eircode, was launched. The codes relate to specific addresses, so there are not general ones for the county or town of Monaghan. So you would need a more specific address to get a code. Post will easily be delivered without their use, just as happened before the launch of Eircode, so it is not necessary to use them. If you need one for a form on the internet, you can use IE.