EDIT: It is possible. Go here, enter your Shadow Era account email address, and click on the mobile phone picture in the top right corner.
I have a Pay-As-You-Go mobile phone which I top up by £15 every month to get free calls and texts to people on the same network as me. I end up with lots of leftover credit that is just accumulating. Sure, I could not top up one month, and pay for my calls, but it sure would be nice if I could instead direct my spare credit towards Shadow Crystals instead.
I got the idea from Comic Relief, where I was able to donate £20 from my phone credit balance, which didn't really feel like £20 as it is money that I otherwise can't make use of anyway.
Here's one such implementation of mobile payments that could be easy for Wulven to support:
http://www.mobiletransaction.org/mobillcash.html
This would also make it easier for people without credit-card to buy crystals.
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