Excellent, informative Callcard site but unfortunately quite dated now. Includes a card list, complete photo gallery and other information. Well worth visiting!
The webpage of Piero Tintori, who wrote the Concise Irish Callcard Catalog
Thanks to the team at archive.org, the Eircom Official collectors page has been semi-saved and is available for reading. For nostalgic purposes or whatever else it is well worth checking out, especially the "News & Updates" section which contains some very useful facts.
Telephone Card Collector online website for UK British Telecom (BT) Phonecards. From the early days of the Landis and Gyr - Sodeco SAIA cardphone in 1981, right up to collecting in 2014 via auction websites such as eBay.
The At mercatino blog contains articles discussing Italian, Irish and many more phonecards from different countries.