You can opt for the standard IVR which gives 1 ‘layer’ of options to press (press 1 for sales, 2 for accounts etc) or you can opt for advanced IVR which can give up to 9 ‘layers’ . 

As an example, the caller could press 1 for sales, and then they would be given another ‘layer’ of options to press (1 for broadband, 2 for mobile, 3 for home phone etc – all still relating to sales).