The caller says they are calling from BT Technical Dept. As my broadband router is showing problems and affecting my Internet speed. This is a scam, Don't give any information or a mobile number, If you do, They can change your internet/password and only allow you future access by asking for a payment. If you're a BT customer you can block the number by dialling BT Call Protect on15721 and listen to the options to block it.