Security verificaton probelm

Hello,
i write this message to the yahoo helper please i have a big problem with my yahoo account that mean i can't signing to my yahoo ( ***@*** because ask me a security question that i forgot about my cellphone number when i created around 2009 or 2010 . the phone number that i put in system when i was creating my account i lost the number and i can't get it again and i think the number was 0797873665. so please help me to log in . i saved alot of important document in to my account and now i can't use because i can't open my account . please show me other way what i shoud do . if there is other security question i can answer , the security question is in the blew
Security Verification
Choose from the following options to confirm your identity for account security.
SMS
+61 *********3665
Voice
+61 *********3665

if there is an othere way or others security question i can answer for that before asked me my birth date or othere security question but now very hard one that i can't answer for that please help me to open my yahoo and if there is anything the company wan to send to me please send my new yahoo account is ***@***
your undrestanding regarding this message great appreciated