From the documentation it seems that, by design, RingCentral webhooks do not support retrying and only sends the notifications once.
Its seems a poor design and will be very difficult to ensure that no notifications are lost. Even high availability environments in the cloud (Azure or AWS) do not ensure 100% availability.
Similar systems will try to publish the notifications a number of times, for a specific period time and only after that, the notification will be dropped and won't be delivered.
This feature is quite important for us when integrating with RingCentral. So I would like to know if a retrying mechanism for webhooks is something you are considering to implement in a future version of your software and if so when will that be available?