Sure, but if you really want to, you can communicate and coordinate. I know it might sound old and all, but before the mobile phones and pagers, people managed to communicate and coordinate. Admittedly it is not as easy, but it is possible.

It might actually be a good thing to try, and to step back without a mobile phone and unclutter our current model of communication and coordination. It would likely involve more commitments (e.g. "we said that we would meet at that space and time") and less distraction.