I will put this out to the brains in the forums, can I achieve the same as a capture if I reference another section of the page. e.g. for the input field say enter the last four numbers of the phone number below? this would mean that the form will be independent to the variable, would this avoid bots etc? Or am I just thinking a little too much Alice in wonder land?
The problem with referencing another section of the page is that the bot is easily programmed by a malicious user to do this for form submissions, and the bot can do this repeatedly creating any number of bogus accounts. So your website would not withstand a targeted attack. You are better off using standard CAPTUA such as http://www.phpcaptcha.org/ .
Thanks for the help, have a great day