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 via conference calls.
Interim meetings are held to focus on specific issues and accelerate the working group process.
Interim face-to-face meetings require Area Director approval and 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. For more information, please see the IESG Statement: Guidance on Interim Meetings, Conference Calls and Jabber Sessions.