How to setup a 5 digit text number which replies to the sender with a payment link?

[UKGiftWarranty]

Title pretty much says it all. I want a customer to text "WORD" to a 5 digit text number and for an autoresponder to reply to them with a payment link to place an order on a website. How easily can this be done and can anybody recommend a provider?

Any guidance would be greatly appreciated!

P.S, I should mention, I need this to work in the UK.

[UKGiftWarranty]

I've now managed to find a UK solution, textvertising which I think fits the bill.

[MM78]

Nice, what's the number to text? I wanna try it!

[UKGiftWarranty]

Will be activating it later today/tomorrow for the start of an FB ad campaign- will gladly share... interested to see if it works overseas (I have not yet tested). The word will be "POTATO". :D

[MM78]

Where's that number?