Advice on Communicating over Internet to dynamic ip address

Hi

We use to to use dial up networking from a retail shop to its head office
and then using Indyftp and Tserversocket and tclientsocket to send messages
and upload/download files.  We use to have a static ip address at the head
office so communicating was easy.

Now we want to do away with the dial ups and make use of ADSL connections
instead.  The only problem is that the adsl host ip address is dynamic.

How would you suggest I do it.

Thanks