We had a bit of a "street war" between payphone operators as apparently there is and may still be signifigant money to be made out of credit card and coin calls made by non-mobile carrying tourists and immigrants, students etc who may not want to make a call at mobile rates back home.
For a while we had at least 3 payphone operators, other than eircom (the former PTT) operating payphones in lucrative areas like city centres, airports etc.
However, the bottom must have dropped out of the market as they've all pulled out the country's third phone company Smart Telecom now have all of the non-eircom sites. They replaced all of the other operators equipment (including those US phones as far as I'm aware) with red totally branded Smart Telecom units.
I seriously doubt that either eircom or smart make much money out of the actual use of the phones but they do provide a very high profile on-street public presence for their brands and logos.
Eircom are required, under the terms of their universal service obligation, to continue to provide payphone service. However, in many place which would have had multiple payphones (e.g. back-to-back payphone stands or clusters of kiosks) they've cut back to just a single heavily branded booth with a multipayment phone. In rural areas some of the phones now only accept credit cards.
The eircom callcard (chip based phonecard that has been around since the mid 1980s) apparently still exists but I have no idea where you can purchase them!
Also, in the city centre areas phone kiosks have started to become WiFi hotspots.
I think the payphone, after a century of service, has finally come to the end of its useful life!
