Mobile money's getting a lot of attention these days, as people get used to the idea of using their mobile phone to manage - and spend - the funds in their bank account.
So Rory Cellan-Jones, BBC technology correspondent, carried out an experiment on his phone, loading a few apps that let him transfer money and pay for things, from cups of coffee to taxi rides. The idea was to see how far he could get without spending any actual cash.
A problem he ran into was this: the technology's still quite new. That means a lot of people (and companies) don't know much about it yet. It also means there's a lot of competition and 'the world' hasn't yet decided which app, technology or way of working really is the way forward.
So Mr Cellan-Jones couldn't buy a coffee in a café that didn't accept mobile money. He tried to make a mobile payment to a friend (who would then pay in cash), but they couldn't get the app to work.
One thing that did work was "a whole range of apps that let you book taxis and minicabs from your phone and have it charged direct to your credit card". The problem here, he said, was that it was "rather too easy to spend money"!
He found that most retailers still don't accept mobile payments, although a few had developed their own apps that let customers pay with their phone.
For the moment, he felt, while "cards will get you most places", there's a lot of work still to be done on mobile payments.