What is the number for Smart Prepaid cellphone subscribers to make a balance inquiry?

According to their website:

• Using your SMART SIM, go to SMART MENU > Buddy Balance/Prepaid Balance to receive your balance information via text.
• Text ?1515 to 214.
• Dial 214#* and press Call to receive load balance via text.
• Dial 121#* and press Call to view regular load balance (and to subscribe to prepaid offers).
• Log-on to My Smart to regularly check your balance online. Registration and linking of account are needed.
• Dial 1515 using your cellphone and you will receive your balance details via SMS (P1/inquiry).