Issue

When placing an outbound call, I receive the Talk error: Cannot connect to number. 

Resolution 

To resolve this error, ensure the number is formatted correctly using the international standard E.164. For more information, see the article: What are the accepted phone number formats for Talk?

If the number is properly formatted and you are still receiving the error, numbers can be blocked by the callee or their external carrier. If the individual callee has blocked the number, try calling from another Talk number to find out why the end-user blocked the number.

External carriers use phone number reputation systems and over time the score can increase. When a number's reputation reaches a certain percentage, blocking is enabled by the carrier.  

To resolve this, you will need to report the calling Talk number to the destination carrier. You can register your number at https://www.freecallerregistry.com/fcr/, which is a shared database where the caller's reputation is shared across multiple providers. 

See the below table for common carrier-specific number reputation registries. 

Carrier Notes Registry
Verizon Verizon provides a link to help allowlist a number. However, Verizon will still pass the information to their third-party vendor.

https://voicespamfeedback.com/vsf/ 

https://reportarobocall.com/trf/# 
Sprint   https://reportarobocall.com/trf/#
US Cellular    https://reportarobocall.com/trf/#
Hiya Hiya services some major carriers and numbers outside of the US. 

https://hiya.com/manageyourcallerid
AT&T Wireless AT&T uses the vendor Hiya. AT&T's Mobility Services indicates to report the number through their Customer Care Support, or by registering the number with Hiya.

https://hiya.com/manageyourcallerid 
Note: Phone number reputation can take time to update. Zendesk can’t predict or guarantee how long it will take for the block to be removed. We suggest that you continue to monitor the situation and report the issue with your external carrier.

Registering your business with your Talk numbers for Shaken/Stir and CNAM is the recommended method for improving call acceptance rate. Once registered for CNAM, carriers will associate the number coming from a valid company and increase the number's reputation. To get started and see a full list of requirements to register for CNAM, see the article: Does Zendesk support CNAM?

For more information on Talk errors, see the article: What are the most common Talk errors?

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