Build a TDOS (Telephone Denial of Service) protection platform

Looking for someone that is capable of building a cloud solution to protect from TDOS attacks. TDOS attack example is that someone is using a Script / Tool to send 500 calls per min to your phone system. The protection must occur before the call begins, from the SIP Invite, and not after the call is completed from the CDR. The cloud platform also needs to have the ability to purchase DID's (Maybe from [login to view URL]) and use them. Here is an example: Right now, a business is purchasing a DID (Virtual Number) from Ring Central / Call Fire/ Etc... He use this number to advertise online (Google / Yelp / Etc..). When a customer calls this DID, the call is being forward to the Office / Cell phone. If someone decide to attack this DID, and send 500 spam calls, all this 500 calls will be forwarded to the Office / Cell phone of the business and will shut the line down. Our system will protect against that. Here is an example: A business is purchasing DID from our cloud solution, he then use this number to advertise online. He forward this number to his Office / Cell phone as usual. So when a customer is calling to the DID he purchased from us, the call will be routed to his Office / Cell phone. When someone decides to attack this number, and send 500 calls, our platform will detect that (From the SIP Invite you can see the IP the calls are coming from) and if an IP is sending let's say more than 3 simultaneous calls a min, our platform will block that IP and by that disable the attack.