Received an automated message on landline regarding internet activity and asked to press1 tp speak to an operator, unfortunately the person that answered pressed 1 and was connected to a person "saying BT open reach how can I help". When said do not have openreach, othr person hung up. Concerned my home phone line is compromised or was connected to premium rate number and need to check my itemised phone bill to see if i will be charged a fee.
The claims of a premium rate call charge being generated by pressing key 1 in response to a scam call, seem to have originated at the end of 2019. It appears to be based on a fusion of lots of different scam-related stories, a particular national newspaper article, various press releases and the plot of a TV drama which came out at the time. The subsequent mash-up story has been repeated by some reputable organisations as well.
The same kind of cautionary media stories regarding scam calls reappeared again in early 2020 but this time without the references to being connected to a premium rate number.
There are ways that scammers can generate premium call charges such as the ‘Wangiri’ missed call scam but I have not yet read any case-specific stories about individual people being scammed in the way the OP suggests by pressing 1 in response to a scam call recorded message.
Two past mentions on the forums here refute the claim too based on the idea that an incoming call can't generate outgoing charges for the customer.
The VM forums are regularly updated with complaints about the annoyance of scam calls. I imagine the forums would be totally overwhelmed if even a small percentage of those annoying scam calls also generated premium rate charges as well!
If you do find you are charged in some way, post back and update the topic with what happened next.