Allowed Country Codes incorrectly detects carrier selection prefix as destination country (V20 Update 9) #9541

[Rafael da Costa]

Hi everyone,


I'm running into what appears to be a limitation or bug in the Allowed Country Codes feature on 3CX Version 20 Update 9 (Build 995 Release - AI 1.4.48).

Environment​

• 3CX Version 20 Update 9 (Build 995 Release - AI 1.4.48)
• Country: Brazil
• SIP provider requires a carrier selection prefix (26) for international calls.

Scenario​

Users dial international numbers in the standard format:

00 + Country Code + Number

Example (Madrid City Hall test number):

0034915240947

The outbound rule is configured as:

• Strip first 2 digits (00)
• Prepend 0026

Result sent to the provider:

002634915240947

This is the exact format required by the SIP provider.

Problem​

The call is rejected by Allowed Country Codes with the following message:
Call from [8715] to [0034915240947] has been rejected by the 3CX Country Blocking Feature [00263].

Reason:
0034915240947 contains Prefix 00263.
Calls to 00263 are not allowed by system.

3CX interprets:
00263...
as:
00 + 263 (Zimbabwe)

instead of:
00 + 26 (carrier selection prefix) + 34 (Spain)

As a result, I would have to enable Zimbabwe (263) just to allow calls to Spain (34), which defeats the purpose of Country Blocking.

Additional testing​

I also tried moving the carrier prefix to E.164 Processing → Add prefix = 26 instead of using the outbound rule prepend, but then the call is no longer sent correctly to the provider.

Question​

Is this expected behavior, or is it a bug?

Ideally, Allowed Country Codes should determine the destination country from the original dialed number (0034...) or provide a way to ignore carrier selection prefixes (such as Brazil's 21, 23, 26, 31, etc.) before evaluating the destination country.


Has anyone found a proper solution for providers that require a carrier selection prefix?

 

[Alejandro_3CX]

Hi @Rafael da Costa within the E164 processing, please set as international prefix 0026 because this is the prefix that your carrier needs to detect you are dialing an international number.

So set the international prefix as 0026 and apply the changes. Then when you dial 002634 the system knows it is an international call to Spain, and if you have the 34 code enabled it will forward the call to the voip provider.