Hi mariama256,
We understand you are unable to receive notifications when called from a specific phone number.
We would recommend ensuring Do Not Disturb is not enabled. You can learn how to do so here: Use Do Not Disturb on your iPhone, iPad, and iPod touch.
We would also recommend, on both devices, to disable FaceTime by going to: Settings > FaceTime, then Restart your iPhone(s), and re-enable.
Additionally, ensure both iPhone are up to date. You can learn how to do so here: Update your iPhone, iPad, or iPod touch.
If the issue persists, it may be worth contacting your carrier to check for any discrepancies.
Hope this helps!
Thank you for using Apple Support Communities.
Cheers!