So this thread and any earlier ones linked to from it is total garbage and imagination by all concerned?
Including the mods to Netgear firmware made by an ISP to circumnavigate the problem?
This post is particularly relevant.
(Edit - who mentioned the address?)
The threads you have referred to have absolutely no relevance to PPP. O2 doesn't use PPPo? on its LLU products. O2 uses DHCP or STATIC on the LLU products.
There is a 'lease' period associated with DHCP - please look up the appropriate RFC (I'll let you GOOGLE it for yourself).
As stated by JonRennie, there is no lease period associated with a PPP session - again, please feel free to look up the appropriate RFC.
However, some ISPs do terminate the PPP session due to lack of activity - I have no idea why they do this. I believe the practice was quite common in Deutschland.
I do not know of any UK ISPs who terminate PPP sessions after a set period of inactivity.