To run a caller ID test (a CLI delivery check), call real handsets in the destination with a known caller ID and record which number actually appears, in which format and on how many calls. A CLI route is only as good as the share of calls that arrive with the right number, so measure it as a percentage over several operators and times of day.
Why CLI delivery needs testing
A route sold as CLI can still lose or change the caller ID along the way. Every carrier in the chain can rewrite the From and P-Asserted-Identity headers, and some routes pass through networks that replace the number with a local one or remove it. The result matters: calls without a recognisable number are answered less often, and callbacks fail. The differences between route types are covered in CLI vs non-CLI routes and local CLI routes explained.
How to run the test
- Pick a test CLI you own, in full international format (E.164, for example 44 followed by the national number). Never test with a number you are not authorised to use. See E.164 number format.
- Get receiving handsets in the destination: colleagues, partners, or a test-call service that has SIMs on the local operators and reports the received caller ID.
- Cover each operator the route claims to reach. CLI delivery often differs by operator, especially between mobile and fixed.
- Make at least 10 calls per operator, spread over different hours. A single successful call proves very little.
- Record for each call: time, dialled number, CLI sent, CLI received, and whether the call connected.
How to read the results
| Received on the handset | What it means |
|---|---|
| Your number, correct format | CLI delivered |
| Your number with a wrong prefix or missing country code | CLI delivered but badly formatted; callbacks may fail |
| A local number you did not send | CLI replaced; acceptable only if you bought local CLI |
| "Private", "Unknown" or no number | CLI removed: the route behaves as non-CLI |
| A different number on each call | Random CLI, often a sign of a grey or SIM based route |
Calculate the CLI delivery rate as calls with the correct number divided by connected calls. Agree in advance what rate the route must reach. Some carriers state a guaranteed share; others make no promise, and the route should then be priced as non-CLI.
Warning signs
- CLI arrives on the first few calls and disappears once volume grows.
- The received number is a local mobile number that changes between calls. This is typical of SIM box bypass, which is illegal in many countries and can be cut off without notice.
- The price for "CLI" is below what legitimate operators charge for international termination in that country.
- The carrier asks you to send a specific number, or a number from the destination country, as your CLI. Presenting numbers you do not have the right to use breaks rules in many markets; see CLI spoofing and robocall rules.
Keep testing after go-live
Carriers change their own suppliers, so CLI delivery can change from one week to the next. Repeat a short test regularly, and every time ASR or callback volume moves without a reason. Add CLI checks to the routine described in how to test a VoIP route.
When you request a route through VoIPMatcher, say which CLI types you can accept and what delivery rate you need, and we source VoIP termination that matches. Request a CLI route.
Frequently asked questions
Why is my caller ID not showing on outbound calls?
Common causes are a route that is really non-CLI, a carrier in the chain that removes or rewrites the From or P-Asserted-Identity header, a number sent in the wrong format, or a destination that blocks international calls showing a local number. Check the number format first, then test the route on several operators.
What is a good CLI delivery rate?
There is no universal figure. Some carriers guarantee a share of calls with the correct number, others promise nothing. Agree the target before testing, measure it as calls with the correct number divided by connected calls, over at least 10 calls per operator, and price a route without a stated guarantee as non-CLI.
Can I test caller ID without people in the destination country?
Yes. Test-call services keep SIM cards on local operators and report the caller ID received on each call, along with connection and audio results. They are the practical option when you have no colleagues or partners in the destination, and they let you repeat the same test regularly after go-live.
What format should a caller ID be sent in?
Send the caller ID in full E.164 international format: the country code followed by the national number, without an international prefix or the national trunk zero. Many networks reject or strip numbers that are incomplete or badly formatted, and callbacks fail when the number arrives without its country code.
Is it legal to display any number as caller ID?
No. In most countries you may present only numbers you own or are authorised to use, and that can be called back. Presenting someone else's number or a random one is spoofing, which regulators such as the FCC and Ofcom restrict, and calls with invalid caller IDs are increasingly blocked.
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Send the destination, route type and target rate. We reply with what we can deliver.