Bug Report: Inbound Caller ID Being Malformatted

Support Help
1

Hi Retell Support,

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.

AFFECTED AGENT
Agent ID: agent_48db948fba67066952fbd3b170 (Mayorazgo: Auto - Inbound)
Inbound Number: +542617640010

ISSUE DESCRIPTION

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:

  1. Post-call workflows (n8n) that use the caller’s phone number for CRM logging, callbacks, and lead routing
  2. Any deduplication or lookup logic based on caller ID
  3. 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.

2

Hey, this seems like a bug in retells logic. If you can provide the call ids it would help a lot in our investigation.

3

Hi, sorry for the delay on the response. Please see the caller IDs below

  • Received as: +261206929110 → Should be: +54 261 6929110
    call_03743d99e6d819d7b7d191802f0

  • Received as: +261205954427 → Should be: +54 261 5954427
    call_7877764d66fac8a0f2dccac9c48

  • Received as: +261205020568 → Should be: +54 261 5020568
    call_50f7f1a19b0f365e4dbce605efc

  • Received as: +261202094667 → Should be: +54 261 2094667
    call_890fcf033b60f3c65081656602f

  • Received as: +261206183113 → Should be: +54 261 6183113
    call_65b24b1f3296c26e1fd887e99a8

4

Hi @steeve

Thank you for providing the call IDs. I’ve escalated this to our team for further review.

We’ll update you as soon as we have more information.

Best regards

5

Hi @steeve

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.

Thank You

6

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.

Countrycode-isoff

7

Hi @shawn

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.

Thank You