Include the option to choose to send sip:domain name when registering

[GoogleCodeExporter]

What steps will reproduce the problem?
1. Register a SIP number

What is the expected output? What do you see instead?
Expected output is "REGISTER xxx.com". Wireshark trace will show that the 
register to "REGISTER  sip:xxx.com". xxx.com is the domain name

What version of the product are you using? On what operating system?
Boghe IMS Client v2.0.173.972
Windows 7 OS

Please provide any additional information below.
I am Huawei IMS engineer, I was trying to use your sip client for testing 
however i am having problem to register the client because the register message 
is send "REGISTER  sip:xxx.com". The desired should be "REGISTER xxx.com"

Original issue reported on code.google.com by [email protected] on 21 Nov 2013 at 3:20