Change the address of service

I have two services which is working in AKS with Istio but serviceA access serviceB through the following address: “http://localhost:5003”.

I have two questions:

  1. How it is possible that although i have deploy those services under Istio those addresses still works and ServiceA manage to consume ServiceB ?

  2. I want to change that address which is defined in the project environment variable (VS2910) to the destination service name so Istio gateway will know which service to activate without the full address “http://localhost:5003”. What shell i do ?