I've recently noticed occasionally that when returning home recently and checking for calls on my house phone that there has been an unsuccessful outgoing call while I have not been at home. The numbers seem to be random. No-one has been in the house to make these calls, so I am at a loss to know how this has happened. My concern is that if these calls get through I could end up with an unwanted bill. The last attempt, yesterday, was to an international number in the Netherlands.
The only mobile numbers I call from the landline are known contacts and I just tried one and it was OK. I've had three of these strange occurrences that I know of. First on 25th September, a known contact locally, second was on 25th September to, I think, an unknown London number with 020 prefix, and the last one yesterday to the Netherlands with 0031 prefix, also unknown. The landline is a BT6610 & I use the Calls feature to check incoming & outgoing calls.