Android SIP API supported features

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http://stackoverflow.com – I am developing an app which uses Android SIP API. I am wondering whether the android api provides support for multi lines calls (Like hold a call and make a new call). I tried to search supported feature but cant find any link explaining this. I went through following links http://developer.android.com/guide/topics/connectivity/sip.html http://developer.android.com/reference/android/net/sip/SipAudioCall.html I am targetting android device 4.0 onwards. and able to manage single line audio call successfully. Note - Please dont suggest me to use any 3rd party Library. I am interested in and (HowTos)