I’m reporting a caller ID formatting issue affecting all inbound calls to one of my agents. The issue has been confirmed not to be on the telephony provider’s side — they have verified the numbers are being sent correctly.
Inbound caller IDs are arriving malformatted in Retell’s call history and metadata. Argentine mobile numbers (country code +54, area code 261, Mendoza region) are being displayed and passed through with the wrong country code (+261, which is Madagascar) instead of the correct +54.
Additionally, some numbers appear with an extra “20” inserted after the area code, adding 2 spurious digits to the number.
Examples from today’s call history (2026-03-06):
Received as: +261206929110 → Should be: +54 261 6929110
Received as: +261205954427 → Should be: +54 261 5954427
Received as: +261205020568 → Should be: +54 261 5020568
Received as: +261202094667 → Should be: +54 261 2094667
Received as: +261206183113 → Should be: +54 261 6183113
Some calls in the same log DO arrive with a correct-looking local format (e.g., 2622372104, 1121679291, 3404512058) — suggesting the issue is inconsistent and may be specific to how Retell processes certain inbound caller ID strings.
IMPACT
This affects:
Post-call workflows (n8n) that use the caller’s phone number for CRM logging, callbacks, and lead routing
Any deduplication or lookup logic based on caller ID
Client-facing records that show incorrect or unrecognizable numbers
CONFIRMED NOT A PROVIDER ISSUE
The telephony provider has confirmed they are receiving and forwarding the caller IDs correctly on their end. The malformatting appears to be occurring within Retell’s inbound call handling or caller ID normalization layer.
REQUEST
Please investigate why Retell is transforming these inbound Argentine (+54 261) numbers into +261 format, and whether there is a normalization or E.164 parsing bug affecting numbers from this region.
Happy to provide full call IDs, transcripts, or any additional data needed.
This is known issue where the country code is missing the in the sip header, which leading to the wrong parsing of the number.
Here is what is sent to retell: ‘sip.phoneNumber’: ‘2616929110’, Then the number is parsed as +261206929110. If your telephony provider can send the caller ID in full E.164 format (e.g., +542616929110 instead of 2616929110), the issue would be resolved immediately. There is no straight forward ways to guess a country code if it is missing.
We will also do more experiments and see how to solve it elegantly.
Hey Shaw - I’m getting a similar issue where the phone number has +1 in the area code, but it is coming in as +95. Any thoughts? Twilio is the provider.
The phone number formatting issue (showing +95 instead of +1) is likely related to how your telephony provider is passing the caller ID in the SIP headers. This is not controlled by Retell and depends on your telephony provider’s configuration.
If we are using Twilio, we can’t use Retell because it will always be malformed liked this? It is a +1 (954) number, so I want to confirm what our options are here.
