Welcome to the RingCentral Community

First of all, don't ride on a very old thread. Instead, make your own question and ask in a new question. You can copy the link of an old question and refer to it in your new question.

The limit of number of subscriptions is 20 active subscriptions per user, per application. This is for both WebHook and PubNub methods together.

However, each subscription can be subscribed for multiple events and there is no limit (or at least very high) of event filters. You can combine different type of events and subscribe them in a single subscription. Then when catching the notification, simple detect the event type and route the event to a proper engine to handle the event,