[ORANGE] Cheapest way to get line 2?

[Christopher Margerison]

I expect this has been asked in the past, but I assume Orange move the 
goalposts occasionally too!

I've got an SE P900 (probably not relevant) on Talkshare 200. My wife and I 
have had our handsets about 15 months.

I want another phone number on line 2, ideally PAYG, but I expect this is 
not allowed.

I'm vaguely aware of dual-sim holders, but I think these only allow one sim 
to be active at a time, which is not what I want. I need a separate phone 
number, with a different ringtone from my main number - but I don't want to 
carry another phone, no matter how small!

Can any of you gurus help me?

Thanks and regards,
Chris.