When you send a text message in any country it is first sent to a Message Centre before being forwarded on to your destination number ie. your Friends and Family.
If you change your Phones network provider, purchase a sim free phone or mistakenly delete the message centre number you will get errors when you try to send your SMS, This is usually due to an incorrect message centre number. There can be other causes but it better to check this first then to be on Hold waiting for Customer Care or in a Shop!
So below I have a list of the Irish Network Centre Numbers for you. In most cases you will find this setting in Text Message Settings under Message Centre Number you just need to edit this to your chosen network.
The + is important so hold the Zero key on your handset until the + Symbol comes up, on some handsets you might have the quickly push 0 twice.
Vodafone Message Centre: +35387699989
Meteor Message Centre: +353857000000
O2 Message Centre: +353868002000
3 Message Centre: +353830000800
eMobile Message Centre: +353857000000
Tesco Message Centre: +353894300000
Postfone Message Centre: +353876999940
48 Message Centre: +353894300000