Thanks so much for popping along today; are you having issues with your line disconnecting?
The timeout should be between 5 - 15 minutes; however this can depend on who initiated the call. It can be an issue with cold callers where the line does not disconnect when you hang up and they stay connected to your line - the only way to do disconnect this type of call would be to unplug the handset from the socket and wait for the line to clear.
Re: Timeout to clear line when caller does not hang up
This sounds like an issue I am currently researching re security in the telecoms industry relating to call clearing. My understanding was that UK telcom providers have now built in an automatic process whereby calls that are left open due to one party not disconnecting are now as a rule cleared after a few seconds in order to prevent fraudulent activity. I know BT launched a campaign around this a few years back.
Are you able to confirm virgin medias current clearing time?