BT Tweaks UK Phone Call Clearing Procedure Again to Stop Fraudster - ISPreview UK
BT has once again tweaked their national telecoms network in order to significantly reduce the time that a phone call connection can be held open (active) after the called party puts their handset down (i.e. such as when you end a voice call), which could make life more difficult for fraudsters.

Related scams work because most people will be unaware that the phone line stays open for a period unless both callers replace their respective handsets (the initiating caller in particular). For example, if you call a friend but only they put their handset down then if they pick it up again later you can still hear them.

Obviously this can be exploited by fraudsters who trick consumers into contacting their bank or another service. A wise consumer, after receiving a potentially suspicious call, will typically replace the handset before getting the legitimate number for their bank and then make the call and all without realising that the fraudster is still on the line (they act as a fake support agent).

Until recently BTs network would wait between 2 and 3 minutes before initiating call clearing to stop the above from happening, although last year this was reduced to 10 seconds with an option to reduce it further in the near future if required (here)

Unfortunately fraudsters have still been using this trick and so the BBC reports that BT has now cut the time to just 2 seconds. Other providers have also made similar tweaks.