I want to search deal with a custom field created called phone number…
is it possible ?
Afraid not, so far we don’t offer searching on only specific fields. You may want to try filtering instead? I think that may work for you.
Hi David
How filters work in api.
I would give this tutorial a look, it will probably easier than me trying to explain 
: https://pipedrive.readme.io/docs/adding-a-filter