Background calls doesnt work with Siphone

What steps will reproduce the problem?
1. I am using TCP connection for making call when application is not in 
foreground and on Lock-screen and also added background calling parameter in 
plist but I am unable to receive call on iPhone 5 when application is running 
in background.

<key>UIBackgroundModes</key>
    <array>
        <string>audio</string>
        <string>voip</string>
    </array>
2.
3.

What is the expected output? What do you see instead?
No Voice call receive in background on iPhone 5.

What version of the product are you using? On what operating system?
Latest pjproject-2.1.0

Please provide any additional information below.

Unable to make calls on background on TCP or TLS protocol with SiPhone.

Original issue reported on code.google.com by catali...@gmail.com on 9 May 2013 at 3:11

uppaljs / siphon

Background calls doesnt work with Siphone #578