Hi ​@MHamm,

Thanks for providing such a detailed explanation of the issue.

Based on the testing you've already carried out, it does sound as though the problem is specific to the messaging route between your iD Mobile number and that particular EE/Spusu number, rather than being a fault with your iPhone itself.

Before anything else, we'd recommend:

• Making sure the sender has not accidentally blocked your number
• Deleting the existing message thread on both devices and starting a new one
• Turning iMessage off and back on if either device is using Apple services
• Performing a network settings reset on your iPhone

As you've confirmed that:

• You can send messages to them
• Other people can receive messages from them
• Your phone works correctly with another SIM

The next step would be to contact our Live Chat team so they can investigate the issue further and, if necessary, raise it with our technical team for a routing check, or ask the EE user to contact their network providers customer service team.

We're sorry for the inconvenience and hope this gets resolved quickly.

Regards,

Gemma M

The iD Mobile Social Media Team