I could resolve this matter with an iphone.
1: Sign in to twitter with safari (not with twitter app. open with safari)
2: Go to “setting” and you’ll find “Phone”. So input your phone number.
3: Go to “Notifications” and switch on. send verification code to your mobile.
4: You’ll get code, so verify it. then now you can control your APP
I’m in Australia. The short & long code method did not work. But from iPhone safari you can verify. Even if you don’t have an iphone. Just borrow it from your friend or family & log in to your twitter account & add your phone number which is doesn’t matter whether iphone or not. any phone is OK. So your phone will get SMS from twitter with a code.verify it & return iphone to your friend.
Hope it helps.