[Acrylic-bob]

I got the trusty calculator out and pressed a few buttons and came up with this...

5 minutes @ £2.50 per minute =£12.50

which gives a possible average of £150.00 per hour

Which in turn gives an average of £1,200 assuming an eight hour day

Which in turn will yield a possible average of £7,200 for a six day week.

Of course you would have to be at it constantly, but I suppose that call times could be adjusted to accomodate the set up time of each separate call.