The ICCPM SIG Webpage provides a portal to access all current SIGs and topics. At the bottom of the page, you have the option to apply to join a SIG or start your own SIG.
Each SIG then contains their own topics of interest. It is within each topic where general discussions are conducted, and where participants can join the conversation by posting their own comments. Additionally, SIGs also hold meetings over video conferences to discuss their various topics.
In general, that’s: ICCPM SIG Webpage > Specific SIG > SIG Topic > Discussions (posts, comments, replies etc.)