WP - Powering voice agents using IBM Watson

W H I T E P A P E R

www.persistent.com

Scalability of the solution:

In order to scale the solution, the components themselves has to be scalable. The scalability aspects of few

components are discussed below

Twilio SIP trunk:

Twilio’s Elastic SIP trunk scales automatically and supports unlimited concurrent calls.

Twilio SIP trunk supports multiple origination URI for efficient load balancing. Calls are forwarded to the

origination URI based on priority and weight of the URI. This allows association of multiple PBX

instances and therefore multiple voice agents -

balancing-and- failover-made-easy.html

Asterisk IP-PBX

: Asterisk PBX can be deployed on a scalable infrastructure such as EC2 or IBM

Softlayer which supports seamless scaling. Asterisk PBX hosted on premise can be scaled by providing

more hardware and software resources

Watson cognitive services

(STT, TTS and Conversation): The Watson cognitive services are cloud

hosted services on IBMBluemix and are scalable.

Orchestrator:

No heavy lifting is done by orchestrator; it delegates calls to respective component.

Orchestrator can be vertically scaled easily. The horizontal scaling is possible via router/load balancer

and as such orchestrator does not maintain any state which might impact horizontal scalability.

Dialog Assistant

: The dialog assistant is domain specific and performs the function of enriching the

response by connecting to other internal/external APIs and/or services. The dialog assistant has to be

carefully designed so as to not introduce great latency during enrichment of the response.

Multi-tenancy of the solution:

Multi-tenancy can be achieved by using these two features:

a. Multiple origination URI configured in Twilio dashboard

b.. Asterisk'sACD -Automatic call distribution queues

TwilioMultiple origination URL:

Twilio places forwards calls to origination URI with lowest priority. If SIP session isn't established, due to busy

endpoint or any other failure, then Twilio dials the next origination URL

Asterisk'sACD -Automatic call distribution queues:

Asterisk's ACD - Automatic call distribution queues where a pool of voice agents wait to answer calls and

incoming calls are queued, usually in a FIFO order, and assigned to next available voice agent.

Limitations:

1. Twilio does not support SIPS (SIP secure) and only supports G.711 audio codec which means other

efficient audio codecs like G.722 or G.729 cannot be used