New sim

[AoifeC3310]

I registered SIM yesterday but phone still saying no SIM card inserted

[dalyer]

What exactly do you mean by "registered"?

Did you activate your SIM? 

• https://community.48.ie/t5/The-Knowledge-Base/Getting-Started-How-to-Activate-your-48-SIM/ta-p/53099

Did that go without any hitches/errors?

Did you insert the SIM into your phone after activating it?

Is your phone unlocked for use on any network? 

• https://48.ie/unlock-your-phone

What make and model of phone is it? 

If you need to contact 48 support about this then see the links in my signature below.