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Integrate your existing telephony infrastructure with SquawkVoice using standard SIP trunking. This guide covers call routing, security, call transfer, and firewall configuration — with BroadSoft (BroadWorks) as a reference platform.

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Call Routing & Setup

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Pointing Your Inbound Number

Configure your telephony platform (e.g. BroadSoft BroadWorks) to route the inbound number to the SquawkVoice SIP domain: 
ai-agent-studio.sip.twilio.com

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Custom SIP Header — Agent Mapping

To authenticate and map the call to the correct AI Agent, your platform must inject a custom SIP header into the SIP INVITE message:
HeaderValue
NameX-SIP-AssistantId
ValueThe Agent ID from SquawkVoice Studio (e.g. 49fc2f4f-0754-4521-a6c1-66912a06d1ae)
You can find your Agent ID in the SquawkVoice Studio under the agent’s settings page.
The X-SIP-AssistantId header is required. Calls received without this header will not be routed to an agent.

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SBC IP Whitelisting

Before your platform can send inbound calls to SquawkVoice, your SBC (Session Border Controller) IP address must be whitelisted on the SquawkVoice SIP domain. This ensures that only authorised traffic is accepted.
1

Provide Your SBC IP

Share the public IP address of your SBC with the SquawkVoice team. This is the IP from which your SIP INVITE requests will originate.
2

SquawkVoice Whitelists the IP

Our team will add your SBC IP to the access control list (ACL) on the SIP domain. You will be notified once the whitelisting is complete.
3

Verify Connectivity

Place a test call to confirm that your SBC can successfully reach the SquawkVoice SIP domain and that the call is answered by the configured AI Agent.
Inbound calls from non-whitelisted IP addresses will be rejected. Ensure your SBC IP is shared with SquawkVoice before going live.

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Security

SquawkVoice enforces encrypted signaling and media on its SIP domain:
ProtocolPurpose
TLSEncrypts SIP signaling
SRTPEncrypts voice media (RTP)
Your platform must initiate a secure SIP session using a sips: URI to connect successfully. 
sips:ai-agent-studio.sip.twilio.com

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Call Transfer (SIP REFER)

SquawkVoice uses SIP REFER to transfer calls — for example, when a caller requests escalation to a human agent. Once the REFER is processed, SquawkVoice drops out of the signaling path entirely.

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Key Requirements

1

Accept SIP REFER without Digest Auth

Your platform must accept SIP REFER from the Twilio SIP domain without requiring Digest authentication. Twilio does not retry a mid-dialog REFER with an Authorization header.
2

Configure the Transfer Destination

In SquawkVoice Studio, navigate to Handoff Configuration → Transfer Rule for your AI Agent. Select a Destination Type (SIP URI or Phone Number) and provide the destination value using one of the three options below.

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Transfer Destination Options

SquawkVoice supports three ways to define where a call should be transferred:

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1. Static Value

Enter a fixed SIP URI or phone number directly. Every transfer from this agent will always go to the same destination. 
sip:192.65.224.204
Use a static destination when all transfers should route to a single, known endpoint — for example, a contact centre SBC.

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2. Variable-Based Destination

Use a {{variable}} to dynamically resolve the transfer destination at runtime. The variable value can be populated via a Pre-Call Action (e.g. a directory lookup) or a During-Call Action (e.g. an API call that returns the right department SIP URI). 
{{departmentSipUri}}
This is useful when different callers need to be routed to different destinations based on their account, region, or issue type.

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3. AI-Resolved Destination

Use the special variable {{interaction.TRANSFER_DESTINATION}} to let the AI Agent automatically determine the transfer destination based on the context of the conversation and the outputs of During-Call Actions. 
{{interaction.TRANSFER_DESTINATION}}
When this variable is used, the AI is given the destination type context (SIP URI or Phone Number) and will resolve the appropriate value dynamically — for example, picking the right department number based on what the caller asked for.
The AI-resolved option is ideal when your agent handles multiple transfer scenarios and you want the AI to intelligently route based on the conversation flow rather than hardcoding every possible destination.

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Firewall Rules

To allow SIP signaling and media traffic from SquawkVoice, add the following rules to your firewall. The IP ranges below correspond to the Twilio North America — Virginia gateway region.

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SIP Signaling

CIDRPortProtocol
54.172.60.0/305060UDP / TCP
54.172.60.0/305061TLS (secure SIP)

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RTP Media

CIDRPort RangeProtocol
168.86.128.0/1810000 – 60000UDP
These IP ranges are specific to Twilio’s North America Virginia region. If your deployment uses a different region, consult the Twilio IP address documentation for the correct ranges.

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Example: BroadSoft BroadWorks Configuration

Below is a summary of a complete SIP integration between BroadSoft BroadWorks and SquawkVoice:
SettingValue
SIP Domainai-agent-studio.sip.twilio.com
Custom HeaderX-SIP-AssistantId: 49fc2f4f-0754-4521-a6c1-66912a06d1ae
TransportTLS + SRTP (sips: URI)
REFER Destination (Escalation)Any valid SIP URI reachable from your telephony platform
SIP Signaling IPs54.172.60.0/30 — ports 5060 (UDP/TCP), 5061 (TLS)
RTP Media IPs168.86.128.0/18 — ports 10000–60000 (UDP)

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Need Help?

If you have questions about SIP integration or need assistance configuring your telephony platform, reach out to our team: