The CoRE working group will have conference calls running every two weeks until IETF 104.  
The exact timing for the 2019 meetings is still to be decided; the present meeting is an exceptional date for 2018.

Most likely main subject for the December meeting is the completion of the CoRE Resource Directory, draft-ietf-core-resource-directory.

We will use the working group WebEx for the calls. The IETF WebEx account does not allow International dialing nor US toll free ("800" numbers), but you can use the WebEx app (e.g., on your smartphone) to connect your device audio, and there's also the option of connection directly from your browser if your browser supports it.