Troublethe red light from flashing constantlyshooting need help please

Uniden Dect 6.0 ( 3 handsets ) I received what appears to be a scam recording call left on my landline 📞 asking me to input a 6 figure pin number to set up my 📞

I have had this 📞 for a few years now this call was just a recording & repeatedly requests I create a new pin & when I didn’t act on that the recording says Goodbye. I cannot delete it in the unusual way of pressing 5 & it won’t clear

There is no linked identification number to this message so I can’t trace or track it nor clear it to stop 🛑 the red light from flashing constantly.

I am on NBN Telstra in Australia 🇦🇺 they have not cleared it either does anyhow know how to correct this please as the message keeps staying on the phone the minute I pick up the handset so frustrating