Landline staying connected for hours when handset not hung up

[freddyfruitbat]

My vulnerable, 90-something-year-old mother has a Talktalk landline, currently on an 'unlimited UK calls' package.  However, she makes so few calls that this is a waste of money and she wants to change to a 'pay as you go' option instead.   But there's a problem...

Mum happens to have a call blocker device on her line to protect her from fraudsters.  It keeps a log of all incoming calls which I can monitor, and over the past few months I've noticed three occasions where she's failed to hang up the phone after making a call.  The line has remained open for up to 8 hours, until for some reason TalkTalk has closed the connection (during the night).    I was very surprised to see this, as in my experience, landlines normally disconnect automatically after a period if there's no activity on the line, surely? Anyway, because she's on a 'free' calls package, Mum's never noticed these long 'calls' - however, if she'd been charged for them at the standard 24p/minute, each of  those calls would have come in at well over £100!

So what I need to know is, if my mother changes to 'pay as you go', will TalkTalk autodisconnect the line if she fails to hang it up, or will she be vulnerable to occasional massive bills like this?

[Arne-TalkTalk]

Can you add the landline number to your community profile and we can check the line.

[freddyfruitbat]

Sorry, should have said "all calls", not just incoming ones - the long calls I mention were definitely outgoing.
Anyway, sounds like I can't risk taking her off that booster.  And given that £16 is only an hour of talk time...

[Arne-TalkTalk]

Usually when the phone is off the hook after a while a loud tone is heard on the receivers end,  I don't think the session is terminated automatically after a while. 

[Gliwmaeden2]

You say it logs incoming calls. So the 8 hour calls were not initiated by her.

If they had been, charges would have kicked in after one hour, as the boost only allows calls up to an hour.

If she does want to chat for more than a few minutes per month, she will quickly exceed the equivalent of the £16.00 charge for the boost. 

Possibly worth checking to see if she can get it added at a discount  - if that offer is available, the current boost would be removed and the new one added at the lower price, with emails confirming all actions if you speak to an adviser.

24p a minute gives you frighteningly little conversation time for a £, and you never know when more time might be needed to talk about an issue that crops up for her, let alone just keeping in touch, @freddyfruitbat.