If are using the main Sinch Build Dashboard, which looks like below:
To contact support, reach out to: onlineteam@sinch.com.
However, if you need support for any of the following platforms, please ensure you go to the corresponding links so your request can be routed correctly:
Sinch has a new single sign-on login experience that will allow you to seamlessly login to any existing Sinch services that you may use - Learn more about Sinch ID.