Validation, either or

[eluser]Colin Williams[/eluser]
You just need a humble little IF control statement:

Code:

$rules['phone1'] = 'required';
if ( ! $this->input->post('phone1'))
{
   unset($rules['phone1']
   $rules['phone2'] = 'required';
}

Note that the condition to match might be more complex than that. You could otherwise have a check_phone_no() callback that essentially does the same thing... might be a little cleaner that way.