Twilio Expert - - Using existing VOIP system with Twilio

We have an existing Twilio account and we would like to try a pilot project to replace our existing VOIP lines with Twilio. 1. We have several SpeedyTel IP Phones that connect 2 offices. One is based in Philipines another based in Singapore 2. PBX is based in our Singapore Office 3. We are experience call quality issues and some feedback that we need to reset the phones each time they on and off the power supply 4. We would like to use Twilio instead for communication using our existing number and Speedy Tel IP Phone 5. We would like IVR to be working and easily changable. (We have disabled our inbuilt IVR because sometimes users cannot press the button to redirect) 6. We also have an existing plugin that is using another SMS provider. If Twilio pilot is succesfully , we will need to replace the plugin api details with Twilio as well. 7. Proper documentation for any custom code and for end user to self support is required Interested Vendors should 1. Indicate their experience on similar project 2. Advise on the turnaround time