That's strange. My sister is on O2 and she has free voicemail.
I'm on O2 PAYG at the moment and I have to pay for voicemail, but it's a once-per-occasion charge. I do, however, go for the "free voicemail" O2 treat when offered it. The existence of such an O2 treat is an added indicator.
It might be, however, that it's another case of the Telco screwing over those on PAYG compared to contract, so contract may be free to access...
As SingaporeAirlines says, it could well come as part of inclusive minutes...
some people on the avforums got their xperia's from mobiles.co.uk and apparently it flags as a special contract on O2's systems that they can't change. One guy got O2 customer service to change his tariff so he had the unlimited web bolt on instead of unlimited texts but others have not been so lucky even after speaking to supervisors.
Just a heads up that it could well end up being £42.50 a month. However with the 40 quid from quidco and 5 months 1/2 price line rental it still works out cheaper than the tmobile deal from expansys. An average of £35.12 vs £40.61 a month over the 18 month contract as I calculate it.
Oh I'm going to raise hell if they try and tell me that I can't change it despite the O2 terms and conditions clearly stating that I can!