Choose your endpoint
Enter the IP address. Free checks use UDP on port 5060; advanced checks let you choose the port and transport.
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SIP open relay testing
Check your SIP endpoints for open relay.
Check for open relay behaviour, inspect responses by SIP method, and repeat your checks after configuration changes.
Free checks on UDP port 5060. Registration required.
Endpoint checkSample result
IP address · Port · Transport
203.0.113.24 : 5060 / UDP
No relay detected
| Method | Outcome |
|---|---|
| OPTIONS | No relay detected |
| REGISTER | No relay detected |
| SUBSCRIBE | No relay detected |
| INVITE | No relay detected |
These sample checks did not observe relaying. This is not a guarantee of endpoint security.
Advanced adds:TCP & TLSFlexible portsScheduled checksOptional Shodan context
A clear view of the response
From an endpoint to a useful result.
Start with a manual check. Use the advanced plan to test other transports and ports, or keep checking on a schedule.
Inspect the evidence
Review OPTIONS, REGISTER, SUBSCRIBE and INVITE responses, including round-trip times and relay observations.
Keep checking
Set daily, weekly or monthly checks on the advanced plan and receive email reports for your configured endpoints.
Pricing & features
Start free. Add the checks you need.
Choose a simple UDP check or more control over your SIP testing.
Beginner
For a quick manual check.
€0 / month
- UDP on port 5060
- Four SIP methods
- Round-trip times
Advanced
For regular endpoint checks.
€10 / month + tax
- Everything in Beginner
- Choose the port; use UDP, TCP or TLS
- Daily, weekly or monthly checks
- Email reports
- Optional public host information from Shodan
Start with a free account. Upgrade to Advanced after confirming your email. Prices are in EUR.
Questions, answered
Before your first check.
What does Kwanlabs test?
Kwanlabs checks for SIP open relay behaviour using OPTIONS, REGISTER, SUBSCRIBE and INVITE. Results describe the responses observed for the selected endpoint and transport.
Is it safe to test my production server?
You can use Kwanlabs to check a production SIP endpoint, but no active test is guaranteed to have zero impact. Each check sends a small set of real OPTIONS, REGISTER, SUBSCRIBE and INVITE requests. Depending on your configuration, these may create logs, trigger security alerts or be handled as calls, registrations or subscriptions.
Start with staging where possible, then check one production endpoint during a quiet period and monitor it. Only test systems you own or have permission to assess.
Does “no relay detected” mean my endpoint is secure?
It means these checks did not observe relaying. It does not establish that every part of your SIP configuration is secure. A missing response or failed connection is inconclusive.
What is included in the free plan?
Manual checks over UDP on port 5060, with responses for four SIP methods and round-trip times. Register and confirm your email to use the free scanner.
Can I schedule checks and receive email reports?
Yes, on the advanced plan. Configure each endpoint and choose a daily, weekly or monthly frequency. Checks and emails run in the service's scheduled window, rather than immediately when you save an endpoint.
What does the Shodan lookup add?
The optional lookup shows publicly available host information, such as known ports and services. It provides context alongside your SIP check; it is separate from the relay result.
Make your next SIP check a clear one.
Start with your endpoint's UDP service on port 5060.