The telAlert product provide a linux / windows binary for a telAlert binary that we can pass parameters to. We don't believe telAlert supports Web Hooks. Would it be possible for a custom integration to run the telAlert binary if it was located on an ActiveGate?
Dynatrace can only sent webhooks for custom integrations. If your target system does not support that, you can write a small web service that accepts the webhook and translates it to the necessary call, e.g. calling a binary.