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1

Create Elastic SIP Trunking in Telnyx

In your Telnyx Mission Control Portal, create a new SIP trunk, select FQDN as the type, and give it a name.Add FQDN:
  • Add sip.retellai.com as the FQDN
  • Select SRV as the DNS record type
Setup Outbound Authentication:
  • Select Credentials as the authentication method
  • Add a username and password — you’ll need these when importing the number to UponAI
Telnyx requires the header X-Telnyx-Username: <username> in outbound calls when using credential authentication. You can add custom SIP headers on the Make Outbound Calls page.
Setup Inbound Settings:
  • Number format: +E.164
  • Codecs: G722, G711U, G711A
  • Transport: TCP (recommended over UDP for reliability)
  • Select your SIP region
Setup Outbound Settings:
  • Create a new outbound voice profile
  • Select it in the outbound setting
2

Move numbers to your SIP trunk

Purchase new numbers or move existing Telnyx numbers to the elastic SIP trunk you just created.
3

Import numbers to UponAI

In the UponAI dashboard, import the number by supplying:
  • Termination SIP URI — Telnyx’s FQDN based on your SIP region (e.g. sip.telnyx.com)
  • Username, password, and any additional SIP headers from your outbound authentication setup
You can also import numbers programmatically via the Import Number API.Once imported, the number behaves like a UponAI-purchased number — visible in your dashboard, usable for inbound and outbound calls. Delete it from the dashboard or via the Delete Number API when no longer needed.