Troubleshooting international call failures

See also

Sources

1. 1
   With Cisco Calling Plan some international destinations and premium services may be unavailable, and customers needing them can open a support case to request availability.

   Get Started with the Cisco Calling Plans · Cisco Calling Plans requirements and limitations · Checked 2026-10-02
2. 2
   During a Cisco Calling Plan trial, international calling and Premium Service call types I and II are blocked.

   Get Started with the Cisco Calling Plans · Cisco Calling Plans trials · Checked 2026-10-02
3. 3
   To allow additional countries in Amazon Connect, the customer opens an AWS Support case with service Connect (Number Management) and category Country Allowlisting for Outbound Calls, listing the countries.

   Countries that call centers using Connect Customer can call by default · How to allow calling to additional countries · Checked 2026-10-02
4. 4
   Amazon Connect StartOutboundVoiceContact returns DestinationNotAllowedException with HTTP 403 when outbound calls to the destination number are not allowed.

   StartOutboundVoiceContact - Amazon Connect API Reference · Errors: DestinationNotAllowedException · Checked 2026-10-02
5. 5
   Amazon Connect StartOutboundVoiceContact requires DestinationPhoneNumber in E.164 format, validated against the pattern \+[1-9]\d{1,14}$.

   StartOutboundVoiceContact - Amazon Connect API Reference · Request Body: DestinationPhoneNumber · Checked 2026-10-02
6. 6
   Amazon Connect's StartOutboundVoiceContact API reference says UK numbers with a 447 prefix are not allowed by default and require a service quota increase request.disputed

   StartOutboundVoiceContact - Amazon Connect API Reference · Note at top of StartOutboundVoiceContact · Checked 2026-10-02
7. 7
   Amazon Connect country allowlisting is default-deny: calls to countries the instance has not been specifically allowed to call are blocked.

   Countries that call centers using Connect Customer can call by default · Note at top of page · Checked 2026-10-02
8. 8
   Amazon Connect instances created in EU (Frankfurt) and EU (London) can call the United Kingdom, Italy, France, Ireland and the United States by default.

   Countries that call centers using Connect Customer can call by default · Instances created in EU (Frankfurt) and EU (London) · Checked 2026-10-02
9. 9
   Amazon Connect instances created in US East, US West, Canada (Central) and AWS GovCloud (US-West) can call the United States, Canada, Mexico, Puerto Rico and the United Kingdom by default.

   Countries that call centers using Connect Customer can call by default · Instances created in US East, US West, Canada (Central) and AWS GovCloud (US-West) · Checked 2026-10-02
10. 10
    Amazon Connect warns that existing instances may be allowed different countries than its published default lists because service quotas have changed over time.

    Countries that call centers using Connect Customer can call by default · Introductory paragraph after the default-deny note · Checked 2026-10-02
11. 11
    Amazon Connect says Japan mobile numbers with prefixes +8170, +8180 and +8190 might not be allowed by default and require a service quota increase request.

    Countries that call centers using Connect Customer can call by default · Japan mobile numbers paragraph (top of page) · Checked 2026-10-02
12. 12
    Amazon Connect's admin guide says UK mobile numbers with prefix +447 might not be allowed by default and need a service quota increase request if they cannot be dialed.disputed

    Countries that call centers using Connect Customer can call by default · UK mobile numbers paragraph (top of page) · Checked 2026-10-02
13. 13
    Cisco's CUBE hardening guide recommends routing only known phone number ranges or SIP URIs rather than catch-all dial-peer destination patterns, as a toll-fraud control.

    Cisco Guide to Harden Cisco Unified Border Element (CUBE) Enterprise Devices · Call Routing and Toll Fraud / Avoid generic dial-peer routing · Checked 2026-10-02
14. 14
    Cisco Unified Border Element by default trusts SIP connections from addresses in its dial-peer configuration; the ip address trusted list command extends that list, and Cisco advises against no ip address trusted authenticate.

    Cisco Guide to Harden Cisco Unified Border Element (CUBE) Enterprise Devices · Call Routing and Toll Fraud / Allow connections from trusted IPs · Checked 2026-10-02
15. 15
    In Cisco Unified CM a device can reach an international route pattern only if the pattern's partition is in the calling device's or line's calling search space; otherwise the call fails.

    Configure Partition and Calling Search Space · Background / partitions and CSS explanation · Checked 2026-10-02
16. 16
    On a Cisco Unified CM IP phone with both a line and a device calling search space, the line CSS partitions take precedence over the device CSS when the two are combined.

    Configure Partition and Calling Search Space · Device and line CSS note · Checked 2026-10-02
17. 17
    When a Cisco Unified CM caller's CSS contains no matching pattern, the user hears reorder (fast busy) or the announcement 'Your call cannot be completed as dialed', and the trace shows NoPotentialMatchesExist.

    Configure Partition and Calling Search Space · Troubleshoot section (symptoms and trace) · Checked 2026-10-02
18. 18
    Genesys Cloud Voice automatically restricts outbound calls to a list of high-cost countries to reduce fraud, for all Genesys Cloud Voice customers in all supported regions.

    Genesys Cloud Voice high-cost country outbound call blocking · Article body (opening paragraph) · Checked 2026-10-02
19. 19
    Genesys Cloud Voice customers cannot edit the high-cost country list or disable a single country code; lifting the restriction requires a support case with Genesys Customer Care.

    Genesys Cloud Voice high-cost country outbound call blocking · Article body (paragraphs on modifying the list) · Checked 2026-10-02
20. 20
    Genesys Cloud no longer sets up the International number plan as a default for new sites; admins add the International classification to the site's outbound route.

    Work with the International number plan · Work with the International number plan; Add the International number plan · Checked 2026-10-02
21. 21
    Under Genesys Cloud Voice Prefix Blocking, new customers have outbound calling to all countries blocked by default, while existing customers start with empty Allow and Block lists.

    Use the Genesys Cloud Voice Prefix Blocking feature to block and allow outbound dialing prefixes · Use the Genesys Cloud Voice Prefix Blocking feature · Checked 2026-10-02
22. 22
    In Genesys Cloud Voice Prefix Blocking, if the same prefix is on both the Allow List and the Block List, the allow rule takes precedence.

    Use the Genesys Cloud Voice Prefix Blocking feature to block and allow outbound dialing prefixes · Allow List/Block List · Checked 2026-10-02
23. 23
    Genesys Prefix Blocking is available only in Genesys Cloud Voice and not in BYOC Cloud.

    Use the Genesys Cloud Voice Prefix Blocking feature to block and allow outbound dialing prefixes · Applicability note near top of article · Checked 2026-10-02
24. 24
    Microsoft Teams outbound call restrictions allow both international and domestic end-user PSTN calls by default.

    Outbound call restrictions - Audio Conferencing & PSTN calls - Microsoft Teams · Introduction and controls table (End-user PSTN calls row) · Checked 2026-10-02
25. 25
    The Teams OnlineDialOutPolicy cannot be customized; administrators assign one of the predefined instances, such as tag:DialoutCPCInternationalPSTNDomestic, with Grant-CsDialoutPolicy.

    Outbound call restrictions - Audio Conferencing & PSTN calls - Microsoft Teams · Using PowerShell (policy table) · Checked 2026-10-02
26. 26
    The Teams End-user PSTN calls control has three options: International and Domestic, Domestic, or None.

    Outbound call restrictions - Audio Conferencing & PSTN calls - Microsoft Teams · Controls table, End-user PSTN calls row · Checked 2026-10-02
27. 27
    Teams dial plans use normalization rules to translate user-dialed numbers into a standardized format, typically E.164, for matching against resources the user is authorized to use and for routing.

    Microsoft Teams Dial plans for phone call routing · What are dial plans? · Checked 2026-10-02
28. 28
    In Teams, normalization rules in a user dial plan take precedence over the tenant Global dial plan, which takes precedence over the Microsoft-managed service country dial plan based on usage location.

    Microsoft Teams Dial plans for phone call routing · Dial plan scopes and a user's effective dial plan · Checked 2026-10-02
29. 29
    For Teams end-user PSTN restrictions, a call is domestic if the dialed number is in the same country or region where Microsoft 365 has been set up for the end user.

    Outbound call restrictions - Audio Conferencing & PSTN calls - Microsoft Teams · Note under the controls table · Checked 2026-10-02
30. 30
    The Microsoft Teams Domestic Calling Plan does not include international calls; the International Calling Plan and the Pay-As-You-Go Calling Plan do.

    Microsoft Teams Calling Plans · Calling Plan options table · Checked 2026-10-02
31. 31
    If a Teams user with a Calling Plan is also assigned an online voice routing policy, calls that match no voice route pattern are routed through the Calling Plan PSTN infrastructure.

    Configure call routing for Direct Routing · Voice routing policy considerations · Checked 2026-10-02
32. 32
    In Teams Direct Routing, a user who has Teams Phone but no Calling Plan has the call dropped when the dialed number matches no voice route in their online voice routing policy.

    Configure call routing for Direct Routing · Example 1: Voice routing with one PSTN usage (note after the third-route diagram) · Checked 2026-10-02
33. 33
    In a Teams online voice routing policy, PSTN usages are evaluated in order and later usages are not evaluated once a match is found, so a catch-all International usage must come after more specific usages.

    Configure call routing for Direct Routing · Example 2: Voice routing with multiple PSTN usages, Note · Checked 2026-10-02
34. 34
    The Teams International Calling Plan and Pay-As-You-Go Calling Plan allow calls to international numbers in 196 countries.

    Microsoft Teams Calling Plans · International Calling Plan; Pay-As-You-Go Calling Plan sections · Checked 2026-10-02
35. 35
    Users on a Teams Pay-As-You-Go Calling Plan cannot make outgoing calls until the plan is funded through Communication Credits or post-usage billing under a Microsoft Customer Agreement.

    Microsoft Teams Calling Plans · How to fund a Pay-As-You-Go Calling Plan · Checked 2026-10-02
36. 36
    For Teams Calling Plans the user's country is based on the location of the user's license, not the organization's billing address.

    Microsoft Teams Calling Plans · Calling Plan options, Note · Checked 2026-10-02
37. 37
    Teams dial-out policy instances ending in PSTNDisabled block all outbound PSTN calls except emergency numbers.

    Outbound call restrictions - Audio Conferencing & PSTN calls - Microsoft Teams · Using PowerShell (policy table rows *PSTNDisabled) · Checked 2026-10-02
38. 38
    A Teams Calling Plan user needs both an international-capable plan and a dial-out policy that permits international PSTN calls; either one alone can block an international call.inferred

    Outbound call restrictions - Audio Conferencing & PSTN calls - Microsoft Teams · Controls table; read with Calling Plan options table in ms-learn-calling-plans-for-office-365 · Checked 2026-10-02
39. 39
    Twilio error 32205 is the Elastic SIP Trunking form of the geo-permission block; 13227 is the Twilio Voice form.

    32205: SIP Trunking: Geo Permission configuration is not permitting call · Error title and product field · Checked 2026-10-02
40. 40
    Twilio describes E.164 numbers as starting with +, holding at most 15 digits, and not having 0 as the first digit after the +.

    What is E.164? · E.164 format section · Checked 2026-10-02
41. 41
    Twilio Voice Dialing Geographic Permissions control which countries and number ranges can be called from both Programmable Voice and Elastic SIP Trunking.

    Protect your account with Voice Dialing Geographic Permissions · Protect your account with Voice Dialing Geographic Permissions · Checked 2026-10-02
42. 42
    Twilio identifies calls blocked by geographic permissions with codes 21215, 32205 and 13227, one for each of three voice call types, searchable in the Console debugger.

    Protect your account with Voice Dialing Geographic Permissions · How do I know if my calls are being blocked by Geo Permissions? · Checked 2026-10-02
43. 43
    In Twilio geographic permissions each country has low-risk and high-risk number ranges, and calls to a high-risk range are blocked when its checkbox is cleared.

    Protect your account with Voice Dialing Geographic Permissions · Set Geo Permissions in the Console; High-Risk Number Ranges · Checked 2026-10-02
44. 44
    Twilio's high-risk ranges cover ranges linked to International Revenue Share Fraud and premium, shared-cost or special-services numbers with higher toll rates.

    Protect your account with Voice Dialing Geographic Permissions · High-Risk Number Ranges · Checked 2026-10-02
45. 45
    Twilio updates its high-risk number range list automatically several times a month and does not publish the ranges; a Phone Number Permission Check tool tests individual numbers.

    Protect your account with Voice Dialing Geographic Permissions · Which countries have the highest risk of toll fraud? · Checked 2026-10-02
46. 46
    Twilio trial accounts can call only low-risk destinations.

    Protect your account with Voice Dialing Geographic Permissions · Limitations · Checked 2026-10-02
47. 47
    Webex Calling authorization codes used to gate international calls at a location are 2 to 6 digits long.

    Configure and Dial International Calling Using Access Code · Configure section, authorization code step · Checked 2026-10-02
48. 48
    When International is set to Require authorization code in Webex Calling, the caller dials the number, is prompted to enter the code followed by #, and the call proceeds only after the code is accepted.

    Configure and Dial International Calling Using Access Code · Verify section (user dialing process) · Checked 2026-10-02
49. 49
    On a Webex Calling desk phone, an international number is dialed by pressing and holding * for at least one second to enter +, then entering the number.

    Make basic calls from your Desk Phone · Dial an international number · Checked 2026-10-02
50. 50
    Webex Calling applies custom digit-pattern permissions on the user, workspace or virtual line first and falls back to the location settings only when no pattern matches.

    Outgoing call permissions for Webex Calling locations · Outgoing call permissions (introductory section) · Checked 2026-10-02
51. 51
    In Webex Calling, a location with an outbound dial digit configured always uses E.164 number format, even if the organization format is set to National.

    Configure dialing behavior for outbound calls · Phone number format / location-level settings · Checked 2026-10-02
52. 52
    In Webex Calling, a user who can dial an international number directly may still fail to forward or transfer a call to it, because the transfer/forward flag for International is separate and defaults to No.inferred

    Outgoing call permissions for Webex Calling locations · Permissions by call type (International row; Allow transfer/forwards column) · Checked 2026-10-02
53. 53
    In Webex Calling outgoing call permissions, the International call type defaults to Block, with transfers and forwards of that call type disabled by default.

    Outgoing call permissions for Webex Calling locations · Permissions by call type (default settings table, International row) · Checked 2026-10-02
54. 54
    Webex Calling classifies a call as International when it goes to a location outside the caller's country and requires an international calling code before the number.

    Outgoing call permissions for Webex Calling locations · Permissions by call type (International Calls bullet) · Checked 2026-10-02
55. 55
    For each Webex Calling outgoing call type or digit pattern an administrator can choose Allow, Block, require an Authorization Code, or Auto-transfer to one of up to three configured numbers.

    Outgoing call permissions for Webex Calling locations · Permissions by call type; Auto-transfer number · Checked 2026-10-02
56. 56
    Webex Calling Premium Services I and Premium Services II call types, which carry fees charged to the caller, default to Block.

    Outgoing call permissions for Webex Calling locations · Permissions by call type (Premium Services I / II rows) · Checked 2026-10-02
57. 57
    Webex Calling has a separate per-call-type setting, Allow transfer/forwards, that decides whether a given outgoing call type may be transferred or forwarded.

    Outgoing call permissions for Webex Calling locations · Permissions by call type (Allow transfer/forwards column) · Checked 2026-10-02
58. 58
    Zoom Phone's International Calling setting has a Manage Country/Region dialog with separate Call Out and BYOC lists of countries phone users may call; the BYOC list applies only to BYOC service.

    Enabling or disabling international calling · How to specify allowed countries/regions for outbound calling · Checked 2026-10-02
59. 59
    Zoom Phone account owners or admins set International Calling at account, group or site level and can lock it so lower levels cannot change it.

    Enabling or disabling international calling · How to enable or disable international calling · Checked 2026-10-02

Documents

Cite this page

WarmTransfer. (2026, October 2). Troubleshooting international call failures. WarmTransfer. https://warmtransfer.net/knowledge/international-dialing-failures

@misc{warmtransfer-international-dialing-failures,
  title  = {Troubleshooting international call failures},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/international-dialing-failures},
  note   = {Verified 2026-10-02}
}