4. SIP Trunk Integration (Cloud Deployment)

4. SIP Trunk Integration (Cloud Deployment)

Overview

This deployment model enables customers to integrate their voice infrastructure with Sestek AI Agents (Cloud) by establishing a SIP trunk from their telephony platform to the Sestek Cloud SBC.

In this architecture, the customer's PBX, IP-PBX, Enterprise Session Border Controller (SBC), Unified Communications platform, or SIP gateway establishes a SIP trunk to a dedicated SBC hosted within the Sestek cloud. The Sestek Cloud SBC receives SIP signaling and media traffic and forwards calls to the cloud-hosted Hummingbird service. Hummingbird manages the voice interaction with Sestek AI Agents by performing Voice Activity Detection (VAD), communicating with Sestek AI Agents for Speech Recognition (SR) and Text-to-Speech (TTS), and managing call transfer operations when required.

This deployment model eliminates the need to deploy Hummingbird within the customer's environment while providing the same SIP call transfer capabilities as the on-premises deployment.

Note: This deployment model requires SIP trunk connectivity between the customer's telephony platform and the Sestek Cloud SBC.

Deployment Responsibilities

Customer Responsibilities

The customer is responsible for configuring and maintaining the SIP trunk between their telephony infrastructure and the Sestek Cloud SBC.

Typical customer responsibilities include:

• Creating and configuring the SIP trunk.
• Configuring call routing rules.
• Configuring codec and media preferences supported by the deployment.
• Configuring firewall and network access rules.
• Providing public IP addresses or Fully Qualified Domain Names (FQDNs), where applicable.
• Performing interoperability and acceptance testing.
• Monitoring and maintaining the customer-side telephony infrastructure.

Sestek Responsibilities

Sestek provides and manages the cloud-side telephony infrastructure, including:

• Cloud-hosted SBC
• Cloud-hosted Hummingbird
• Connectivity between the Cloud SBC and Hummingbird
• Connectivity between Hummingbird and Sestek AI Agents
• Platform monitoring and maintenance
• SIP endpoint information required for customer configuration
• Support during interoperability testing and deployment

Integration Process

The following high-level steps are required to complete the integration:

1. Configure a SIP trunk from the customer telephony platform to the Sestek Cloud SBC.
2. Configure routing rules on the customer telephony platform to forward the required inbound calls to the SIP trunk.
3. Configure the corresponding SIP trunk and routing configuration within the Sestek platform.
4. Associate the required phone numbers (DIDs) with the appropriate Sestek AI Agents project.
5. Perform interoperability and end-to-end acceptance testing.
6. Move the integration into production.

How It Works

The following sequence describes a typical voice interaction:

1. A caller places a call to a phone number configured on the customer's telephony platform.
2. Based on the configured routing rules, the call is forwarded through the SIP trunk to the Sestek Cloud SBC.
3. The Cloud SBC forwards the call to the cloud-hosted Hummingbird service.
4. Hummingbird establishes the SIP session and initiates a voice conversation with Dataflow.
5. Dataflow performs Voice Activity Detection (VAD) on the incoming audio stream.
6. When speech is detected, Dataflow segments the audio, associates it with a unique conversation identifier, and sends it to the Speech Recognition (SR) service for transcription.
7. Dataflow sends the transcribed text to the Sestek AI Agents service.
8. Sestek AI Agents processes the request and determines the appropriate response based on the configured project flow.
9. Sestek AI Agents generates a text response.
10. The generated text is returned to Dataflow, which converts it into an audio stream using Text-to-Speech (TTS).
11. Dataflow streams the synthesized audio back to the caller through Hummingbird over the established SIP session.
12. This process continues until the conversation ends or the call is transferred to another destination.

Call Routing

Each configured phone number (DID) can be associated with a specific Sestek AI Agents project.

When an incoming call reaches Hummingbird through the Sestek Cloud SBC, the called number is identified from the SIP signaling information and matched with the corresponding project configuration.

If no matching configuration exists, the call is rejected or handled according to the configured routing policy.

Prerequisites

Before starting the integration, ensure that:

• The customer telephony must supports SIP trunking.
• Network connectivity between the customer environment and the Sestek Cloud SBC has been established.
• Required firewall rules have been configured.
• The required Sestek AI Agents project has been created and published.
• Required phone numbers (DIDs) have been assigned for routing.

Testing

Before moving the solution into production, Sestek recommends validating the following scenarios:

• Successful SIP trunk establishment
• Inbound call routing
• Call transfer functionality
• Multiple concurrent calls
• Call termination scenarios

Successful completion of these tests confirms that the SIP trunk integration is operating correctly and is ready for production use.