If you are planning to use this in the survey, then you'll need to ask your admin to provide you the externally exposed ip of the API.
As in the survey flow, the web service is called from your computer, in the live survey, it's called from Qualtrics' server.

Hi Ahmed,
Could you please provide some more information in detail. Please note that I have the ip address of the external API with me and whenever I am trying to do run test in webservice getting error as The specified network port is not allowed , Local network addresses not allowed .

If you're getting this message as a response, then that means that the webservice you are calling isn't allowing requests from your particular network address. I assume it could be because you are calling the external ip from a network that has internal access configured.
If Qualtrics is raising this issue, then you'll need to contact support to see if those specific ports are open.

Ok Ahmed, I will reach to support team then as I am able to access the same API in browser from same network. Facing issue only when calling from Qualtrics.