Don't phone verify your account with the old number. I did that and it resulted in instant ban. Every time I get a PVA I use an iPhone app called Burner which lets you purchase ($1.99) new phone numbers for any area code you want. In the USA we don't have cheap sims, so $1.99 is not such a bad deal I guess. Each phone number can only be used about 4 times. On the 5th time Instagram will give error message "use another number please."
I got an account banned using the free sms/burner versions. If the app gives you a free number to try out, chances are its already flagged with Instagram. The app I use, must pay $1.99 to get the first number. I've had 6 burner phones, all usa numbers, all verified about 24 accounts.