I'm using these settings
APN - 48months.liffeytelecom.com
MMSC: http://mmc1/servlets/mms
MMS Proxy: 10.1.11.19
MMS port: 8080
MCC: 272
MNC: 11
Authentication type: PAP
APN type: default,supl,mms
From this link
http://community.48months.ie/t5/Need-Help/Internet-Settings/m-p/78#M1I changed the authentication to PAP this am so will see if this helps.
I thought the APN settings were just to do with data, not calls and texts. Am I wrong in this?