Outside of Google ads
Custom Google forwarding numbers shouldn’t be used for any other purpose (except where you used these numbers for website call conversion tracking). These numbers are a property of Google and can change or be reassigned at any time.?
as above Google guideline We should take a separate phone number for website call conversion tracking? or same no i can use for outside call (not form website call conversion tracking) but there is a confusion how Google decide this call is outside or form website call conversion tracking?
Re: Outside of Google ads
Are you asking what google means when they state that the phone numbers should not be used outside of website conversion tracking? I think what they are trying to say is that you should not incorporate Google's call forwarding numbers into other media (mailers, etc) because they can be reassigned to other advertisers. Therefore, if your customers tried to call they might not be able to reach you. There are other call tracking vendors if you would like to track additional vendors in addition to Google. You should check out IfByPhone, Telmetrics, and Marchex. There are even more than that - but those are the ones I have used.
I'm not sure exactly how Google's dynamic website call tracking works but I know that others work by marrying the time stamp of the call to the time stamp of clicks/impressions. If you used the call tracking number offline or for other online media such as local listings, it would mess up Google's ability to match it to the appropriate session and it would mess up your data.
Hope this helps!