Since I am a Senior System and Network Engineer I have a pretty good experience with FreePBX, especially given to the fact that we use it in our office, for all the calls which goes to our Technical Support.
But, I have lack of experience with SOAP 1.2 API, so everything regarding IVR and call flow, is a very easy task which I can do in about 1-2 days, what about SOAP API, I will need a little bit more time, to figure it out how to deal with it.