I am advised by the Revenue Commissioners that charitable donations made by text message, excluding any fees charged by the telecommunications provider or other service provider, are outside the scope of Irish VAT. Any fees charged by the telecommunications service providers in connection with the facilitation of donations are liable to VAT at the standard rate of 23%.
The VAT treatment of charitable donations made by text message is set out in Revenue's eBrief 29/11 which is available at http://www.revenue.ie/en/practitioner/ebrief/archive/2011/no-292011.html.