Can i know what the error message you get please when it fails to verify the phone number during register?
You can use a new proxy which has been used to create account, this may help you pass the phone verification step. But whether to ask for phone verification is determined by Google but not our software. It is just my suggestion, you may try.
Useragent is not necessary during register. But you can use the useragent too. Here is the how the useragent looks. And you can find many in your search engine. But please confirm if this useragent works before entering it to the software.
Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/66.0.3359.139 Safari/537.36
Waiting for your news.