Treat the connection and outbound profile as separate controls
Telnyx documents SIP connections for authentication and inbound handling, with Outbound Voice Profiles controlling outbound routing and limits. Inspect both objects when a trunk receives calls but cannot place them.
Create a deployment record that links the numbers, connection, outbound profile and owning administrator. Check the allowed destinations and spending controls before a pilot. A successful connection does not establish that the outbound policy permits every destination.
Documented service facts
Reviewed 2026-09-08. Compare SIP trunk services →
Outbound authentication
DocumentedCredential or IP-based connections; FQDN inbound routing is paired with credentials or IP authentication outbound.
SIP registration
DocumentedSupported with credential connections; IP and FQDN delivery have different setup requirements.
Inbound delivery
DocumentedAssign numbers to a SIP connection; outbound calling also uses an associated Outbound Voice Profile.
Inbound failover
DocumentedRetries follow configured routes and supported failure conditions; optional call-forward-on-failure is documented.
Number and regional availability
Not verifiedRegional signaling is documented. Exact number inventory, country eligibility and porting availability are not verified for your account.
Audio codecs
DocumentedDocumented audio list includes PCMU, PCMA, G.729, G.722, Opus and AMR-WB; actual end-to-end negotiation varies.
T.38 fax
DocumentedListed as a supported optional capability; validate the intended fax route and endpoint.
Signaling and media encryption
DocumentedTLS and SRTP are documented; TLS connections require version 1.2 or higher.
Call-start capacity
Not verifiedYour effective connection concurrency and call-start limits are not verified; confirm them before a burst test.
Emergency calling
DocumentedDynamic E911 supports provisioned address/endpoint data and a location-based workflow; activation must be verified before reliance.
Pricing model
DocumentedPer-minute calling and an inbound channel option are published. Confirm included traffic, number costs, destination rates and optional charges.
Administration and support
Not verifiedConnection and outbound-profile APIs are documented. Your support commitments and commercial agreement remain unverified.
SMS and MMS
Not verifiedNumber-specific messaging eligibility and campaign requirements are not verified by this trunk review.
Choose authentication around the real network
Credential registration, IP-based setup and FQDN inbound routing solve different network requirements. The FQDN choice still has a separate outbound authentication method. Confirm how the PBX discovers destinations and what happens when its public address changes.
For a dynamic-address deployment, test after an actual address or transport interruption. For an IP-based deployment, test every configured origin and backup path. Avoid recording a single green registration indicator as the acceptance result for all these models.
Test fallback with the intended failure
The routing documentation distinguishes conditions that trigger another route from responses that stop that process. A busy or deliberately rejected call is not equivalent to a transport failure.
Prepare separate tests for an unreachable PBX and a reachable PBX returning the organization’s intended response. Record the attempted destinations and final caller experience. If PSTN forwarding is enabled, include that route’s identity, permission and charge implications in the operating plan.
Keep transport documentation current
The network reference documents TLS/SRTP and notes certificate changes during 2026. Compare the current provider guidance with the trust store and protocol capabilities of the installed SBC or PBX. Do not weaken certificate validation to make a failed test pass.
Check the offered and accepted audio codec on each leg. The provider’s supported list does not establish what a downstream carrier or remote endpoint negotiated. Fax needs its own end-to-end acceptance test even when T.38 is listed.
Complete the account-specific evaluation
Dynamic E911 documentation warns that newly provisioned endpoint data can require activation time and recommends advance provisioning. Confirm status and use the documented non-emergency test procedure before relying on a location.
The pricing page presents both usage charges and an inbound channel option. Ask which traffic the selected option covers and how the account’s limits are set. Exact number eligibility, porting, messaging and contracted support remain questions to resolve for the actual order.
Sources & applicability
Primary references for the technical details above. Operational examples and planning checklists are VoIP.info editorial guidance.
- Telnyx service objects ↗
- Telnyx authentication ↗
- Telnyx routing retries ↗
- Telnyx network, codecs and encryption ↗
- Telnyx TLS minimum ↗
- Telnyx emergency location workflow ↗
- Telnyx pricing ↗
Examples require adaptation to your topology. No live PBX or hardware testing is claimed.