SRV Records

DNS SRV (Service) records enable automatic failover and load distribution for SIP connections by resolving to multiple Telnyx signaling IPs with priority and weight parameters.

SRV record format

Telnyx SRV records follow RFC 2782 DNS SRV specification:

_service._protocol.domain TTL class SRV priority weight port target

Example:

_sip._udp.example.com. 3600 IN SRV 10 10 5060 sip.telnyx.com.

Parameters

Parameter	Value	Description
Service	`_sip`	SIP service identifier
Protocol	`_udp` or `_tcp`	Transport protocol (UDP recommended)
Domain	User’s domain	The domain being configured
TTL	`3600`	Cache duration in seconds
Class	`IN`	Internet class (standard)
Priority	`10`	Lower values preferred (use same value for all Telnyx entries)
Weight	`10`	Load distribution ratio (equal weight for balanced distribution)
Port	`5060` or `5061`	5060 for UDP/TCP, 5061 for TLS
Target	`sip.telnyx.com.`	Telnyx regional FQDN (note trailing dot)

Regional FQDNs

Configure SRV records to point to the Telnyx region closest to the user’s infrastructure:

Region	FQDN	Resolves to IPs
US	`sip.telnyx.com`	`192.76.120.10`, `64.16.250.10`
Europe	`sip-eu.telnyx.com`	`5.172.39.10`, `5.172.39.25`
Canada	`sip-ca.telnyx.com`	`193.108.220.10`, `193.108.220.25`
Australia	`sip-au.telnyx.com`	`193.108.104.10`, `193.108.104.25`

For the most current IP addresses and additional regions, see sip.telnyx.com.

Configuration examples

Basic configuration

Single SRV record pointing to US region:

_sip._udp.example.com. 3600 IN SRV 10 10 5060 sip.telnyx.com.

TLS transport

For encrypted SIP signaling on port 5061:

_sip._tcp.example.com. 3600 IN SRV 10 10 5061 sip.telnyx.com.

Multi-region redundancy

Route to US as primary, EU as secondary:

_sip._udp.example.com. 3600 IN SRV 10 50 5060 sip.telnyx.com.
_sip._udp.example.com. 3600 IN SRV 20 50 5060 sip-eu.telnyx.com.

Priority 10 (US) is preferred over priority 20 (EU).

Benefits over A records

Feature	SRV Records	A Records
Automatic IP failover	Yes (resolves to multiple IPs)	No (manual configuration required)
Port specification	Included in record	Hardcoded in PBX config
Load balancing	Weight-based distribution	Requires DNS round-robin
Protocol awareness	Transport specified in record	Assumed by application
Regional routing	FQDN-based	IP-based

Verification

Verify the user’s SRV record configuration:

dig _sip._udp.example.com SRV

Expected output shows multiple A records for the target FQDN:

_sip._udp.example.com. 3600 IN SRV 10 10 5060 sip.telnyx.com.

;; ADDITIONAL SECTION:
sip.telnyx.com. 300 IN A 192.76.120.10
sip.telnyx.com. 300 IN A 64.16.250.10

Test resolution to IP addresses:

dig sip.telnyx.com A

DNS provider configuration

Most DNS providers support SRV records through their control panel or API. Common DNS providers:

Route 53 (AWS): Record type “SRV”, value format 10 10 5060 sip.telnyx.com
Cloudflare: Record type “SRV”, configure service, protocol, priority, weight, port, target separately
Google Cloud DNS: Use gcloud dns record-sets create with --type=SRV

API example (AWS Route 53):

{
  "Name": "_sip._udp.example.com",
  "Type": "SRV",
  "TTL": 3600,
  "ResourceRecords": [
    {
      "Value": "10 10 5060 sip.telnyx.com."
    }
  ]
}

Failover behavior

SRV records work with Telnyx automatic failover:

DNS query resolves sip.telnyx.com to both IP1 and IP2
SIP INVITE sent to IP1 (primary)
On timeout or error, retry to IP2 (secondary)
If all IPs fail, attempt next priority SRV target (if configured)

See Failover and Retries for complete failover logic.

Troubleshooting

SRV record not resolving:

Verify trailing dot on target FQDN (sip.telnyx.com.)
Check TTL has expired if you recently updated
Confirm DNS propagation: dig @8.8.8.8 _sip._udp.example.com SRV

PBX not using SRV record:

Some PBX systems require explicit SRV lookup enablement
Configure PBX to use domain (example.com) not IP address
Check PBX logs for DNS query behavior

Unbalanced load distribution:

Verify equal weight values for balanced distribution
Some SIP stacks cache first resolved IP
Consider implementing client-side round-robin

Getting Started

Authentication

Configuration

Routing

Network Configuration

Features

STIR/SHAKEN

Emergency Calling

Troubleshooting

SIP Integrations Guides

API Reference

For AI Agents

SRV record format

Parameters

Regional FQDNs

Configuration examples

Basic configuration

TLS transport

Multi-region redundancy

Benefits over A records

Verification

DNS provider configuration

Failover behavior

Troubleshooting

​SRV record format

​Parameters

​Regional FQDNs

​Configuration examples

​Basic configuration

​TLS transport

​Multi-region redundancy

​Benefits over A records

​Verification

​DNS provider configuration

​Failover behavior

​Troubleshooting

SRV record format

Parameters

Regional FQDNs

Configuration examples

Basic configuration

TLS transport

Multi-region redundancy

Benefits over A records

Verification

DNS provider configuration

Failover behavior

Troubleshooting