Addition Required in SIP App (linphone)

We have a running app on the apple store. We have the complete source code, below are some of the modifications required. 1. When a new registers, we are sending them an SMS to verify the number, a few changes is required which will be shared in detail with the selected freelancer. 2. We require push notification in the app, we also one one idea how to do it. 3. Linphone code has already chatting present in it. We had hidden it in the start, we want that to be shown back to the end user. These are the changes required, please note that, the we will set milestones and after successfully testing the milestone payment will be released. if you have experience with linphone it will be a plus