Troubleshooting Tip: SMS gateway using HTTPS protocol unable to send a text message: HTTP request failed

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Description	This article provides a solution for the following error when it is encountered in the SMS gateway (HTTPS protocol): 'Unable to send a text message: HTTP request failed (url: https://x.x.x.x/, status: 0, res: ). Please check your configuration'.
Scope	FortiAuthenticator SMS Gateway HTTPS protocol.
Solution	The error message is as follows:   Packet capture is shown as below: Connection closed by FortiAuthenticator after Change Cipher Spec. Resolution: Obtain the SMS gateway server CA certificate from the respective party. Ensure that this CA certificate is imported into FortiAuthenticator by going to Certificate Management ->Certificate Authorities > Trusted CAs. It is possible to manually import the CA certificate or 'Learn Certificate'. Ensure the API URL hostname matches the server certificate common name.   Ensure FortiAuthenticator can resolve the URL hostname to an IP address.