[izik]

Why - I suppose that government want to get tactical advantage over protesters by limiting information flow and making protest coordination more difficult.

How - both deep packet inspection + filtering and primitive solution - making communication services (mobile and broadband) stop functioning. Such things happen already in the past in Turkey, Egipt, Iran.

[Tepix]

Depending on the type of filtering you could try to tunnel data across UDP (DNS?) or ICMP packets or configure hosts on both ends to ignore TCP RESET packets.