i am in ireland with a NZ voda and I want to send test messages to phone on IE (ireland) Voda network.
I send the message but it is not received.
The person with th IE Voda phone can text me successfully, but my reply to them is not receieived.
I can successfully ring the IE Voda from my phone so the number format is correct.
Roaming is normally off.
My phone is on a NZ plan
Just check this person hasn't accidently blocked your number - happens all the time.
Androids you can for example block just messages so phone calls can still get through. Check settings see if anything shows up under block/spam options.