Just a quick note that we in the UK can now take credit card payments by smartphone with the new device and app from izettle.
US customers have been able to do it for a while via chase bank, (I even paid for my haircut like this last month in Cocoa Beach) but now we can get it in the UK, tried it this week, works great and is very handy to have at shows or promotions etc. Cost £20 for the device and 2.75% per transaction. You can also take payment via text that re directs the customer to a secure payment page.
I have nothing to do with
izettle.com
John
I have been using an app on the iPhone called CC Terminal (costs £10 one off fee for the app) for the last 2 years. It can be configured to work with Paypal Pro API very easily. No chip and pin though so only really good for over the phone transactions. It processes card at your paypal pro rate, I currently pay 20p + 1.9% pr transaction. Money from purchases is usually in my bank account instantly (as soon as I transfer it from paypal that is).
For Face to face transactions where I want to use Chip and Pin I use Elavon Mobile Merchant. Full on Chip and pin solution, costs £99 a year for the Bluetooth terminal and I pay 2.99% per transaction. A little more expensive than CC Terminal but worth it for a proper Chip and Pin Solution. Money is in my account within 24 hours.
Just my 2 pennies worth 
I’m very happy with both these and have worked flawlessly for me.