I should think that the phone line from the socket goes in the in and then the out goes to the modem.
Motto of the day: Never trust your ISP. I would give it a few days to see if they are at fault and not you Barra. Mine never admits to anything and I don't bother phoning them anymore if the connection goes down. Mine has an automatic cut-off after 2 hours of inactivity but in practice I can't actually tell that this takes place since one you refresh it seamlessly reconnects again. If all else fails, try replacing cables (if possible) one by one. After that, it may possibly be a faulty modem?
so I could deal with all my mail through Plusnet