The work of the IETF is largely conducted over mailing lists; however, some working groups also occasionally hold "interim" meetings, either face-to-face or virtually.
Interim meetings are held to focus on specific issues and accelerate the working group process.
A complete list of upcoming interim meetings is available on the IETF Datatracker. Interim face-to-face meetings are scheduled by Working Group chairs and require Area Director approval. They must be announced at least four weeks prior to the meeting. Conference calls and jabber sessions must be announced at least two weeks prior to the meeting, and require Working Group Chair approval.
A list of past interim meetings is also available on the IETF Datatracker. Archives for each meeting include meeting agendas, minutes, participation records, as well as slides and documents presented and discussed during the meeting.
For more information about interim meetings, please see the IESG Statement: Guidance on Interim Meetings, Conference Calls and Jabber Sessions.