SMS - Known restrictions for JP

Due to restrictions by the carriers and also government regulations, these are some known restrictions that will affect messages/calls to JP (+81)

Sender ID for messages cannot specify numbers that will be considered as domestic numbers in JP (i.e numbers that starts with +81 or 0) to avoid number spoofing.
KDDI (au) do not support alphanumeric Sender IDs.

These can change anytime based on carrier or government restrictions without pre-notice.