So... you need to have your mobile app hit your local web serivce (that runs on IIS Express) and debug it. Follow these articles:

NetSH Commands

Summary

  • Configure your bindings in IISExpress: C:\Users\YourUser\Documents\IISExpress\config\applicationhost.config
  • Add the binding for your the ip address of your machine
<site name="SomeSite" id="32">
	<application path="/" applicationPool="Clr4IntegratedAppPool">
		<virtualDirectory path="/" physicalPath="C:\dev\code\someSite" />
	</application>
	<bindings>
		<binding protocol="http" bindingInformation=":7299:localhost" />
		<binding protocol="http" bindingInformation="*:7299:192.168.0.6" />
	</bindings>
</site>
  • Run this command in an elevated command prompt
netsh http add urlacl url=http://192.168.0.6:7299/ user=everyone 
  • Add a firewall rule: Inbound port 7299, allow

  • Once done, switch your bindings back:

<bindings>
   <binding protocol="http" bindingInformation="*:7299:localhost" />
</bindings>
  • Run this command to remove that rule:
netsh http delete urlacl url=http://192.168.0.6:7299/