Results 5 issues of Slavik

This PR will add `onCancel` delegation for Session. This can help developers to detect CANCEL events while call is ringing on the client and fire any action needed. It can...

**Describe the bug** For some reason when using "UserAgent.stop()" function it takes around 30 seconds to stop everything until it responses with the appropriate promise. What I'm trying to achieve...

bug

Hi, I'm struggling for a few days already regarding if SIP.JS allows to make outbound out-of-dialog REFER requests. Currently I'm working with 0.16.1 and found some references in the oldest...

enhancement

Adding the ability to add `extraHeaders` for the `unsubscribe` method. Example: ``` var subscriptionUnsubscribeOptions: SubscriptionUnsubscribeOptions = { extraHeaders: [ `X-Test: test` ] }; subscriber.unsubscribe(subscriptionUnsubscribeOptions); ```

Hi, I'm having an issue to compile the new 0.21.2. When doing `npm run build` as usual it is saying that there are lots of lint errors, so I'm trying...