NOTICE TO ALL CUSTOMERS
If you are getting calls from +33 1 76 74 36 80, don’t panic, these calls seem to proceeding from the Talk Talk telecoms network, mostly mobile phones it would seem. This is a configuration fault on the Talk Talk network, which is easily rectified by them.
Basically someone has accidentally set the CLI override on the outbound call channels to show a single CLI (caller ID) +33 1 76 74 36 80.
The best way to get this resolved is for any Talk Talk customers experiencing the same problem when they make calls, that if their phone number is showing up as +33 1 76 74 36 80 is the recipients phone you are calling, then you need to report this fault to Talk Talk.