I receive emails and questions daily from singers asking me how to increase the range of their singing voice. It is quite simple to increase the vocal range.
First, you need to start with good vocal technique and work daily. The singer will need to strengthen the vocal muscles and breathing stamina of the range they are currently singing in.
After this is achieved you begin expanding range on both sides of the current vocal range. You will see results quickly if you have good vocal technique and are disciplined to work on your voice daily.
My DVD/CD Vocal Builder Series has helped many singers increase their vocal range, check it out on my website store.