PAYG sim with credit showing "unregistered sim"

[Userxxxzzz]

Why is my PAYG sim showing as "unregistered sim" on the screen?

There is lots of credit on it.

[XRaySpeX]

On what screen? Have you registered it to MyEE, altho' you don't need to to use it?

[Userxxxzzz]

On the phone screen.

I turn the phone on and it says "unregistered sim" - it is showing full signal.

[XRaySpeX]

What does texting AL to 150 from it fully report verbatim?

[Userxxxzzz]

Text AL to 150;  The phone says "sending failed"

[XRaySpeX]

Have you put an EE SIM into an EE or unlocked phone?

[Userxxxzzz]

The phone is an LG KG275 - it doesn't have any network branding and only LG logo is showing when you power on/off.

Is there a way to check a phone if it is unlocked?

[XRaySpeX]

1 way is to put another network's SIM in it You have & it implies it's locked to some network other than EE.

Where did you yourself get this phone originally?

I don't know that phone but look for the name of its network in:

• Connection Settings / Mobile Networks / APNs
• About Phone / Status

[Userxxxzzz]

My friends Lycamobile SIM works in it.

In the middle of the screen it says "O2" and at the bottom "LYCAMOBILE"

I bought this phone from someone used as a backup.

There is no;

• Connection Settings / Mobile Networks / APNs
• About Phone / Status

Just;

Menu--> Settings --> Network Selection --> Automatic/Manual/Preferred

This is an old style GSM phone not a smartphone.

[Kirigaya_Kazuto]

Does the SIM work in another phone?

When was it last used? iirc, if SIMS aren't used on PAYG for 6 months it gets kicked off/de-registered from the network.