The PushCoin Point of Sale (POS) systems need access to the following web Internet resources on TCP ports 80 and 443:
Network time sync over NTP
Android devices synchronize its clocks through access to NTP servers at pool.ntp.org and all sub-computers under *.pool.ntp.org like 0.pool.ntp.org
NTP is a UDP-based service using a well-known port 123. We recommend opening traffic on UDP/123 to any remote host.
A stock Android device such as a tablet or a smartphone contacts Google Play servers for checking internet connectivity, push notifications and software updates. These services will fail to operate if the Google Play ports TCP and UDP 5228 are blocked.