PBX skilled person - individual contractor only please

REQUIREMENTS : -we use API with plivo -We need dial pad after agent places call, currently agents cannot input extension. -We need an autodialer from the list we input (currently agents need to dial manually) and plivo doesn't have auto dial capability (CHECK on this) if not we will have to go open source with asterisk pbx, -Company with PBX need to be able to manage DID (phone numbers) and assign number to agents, administrator and super admin account, -Lower the cost per minute and per text (that is why we need to migrate to asterisk open source) -Lastly I need to be able to receive text message for social media account companies from the did (phone numbers assign or created for the agents) since we will need that for our social media Those are the main needs currently for the PBX system Like Check the Pilvo APi and than let me know how would you do this? and is it possible or not? I will share the server details to check the code too.