When you send the topic and all about the meeting or conference you should mention, that any mobile electronic gadget is prohibited of use in the meeting.
Anyway at any meeting I anticipated, the meeting facilitator always started with ...Please all the electronic gadget and mobile phone should be turn off, then continued with the agenda of the meeting. These were the meetings that had nothing to do with electronic though.
To be effectived, the meeting should have a rule and respected for all.
