Transfers
MSISDN - Blacklist
The blacklist is implemented at HUB2 level, not at provider level, although providers can integrate similar mechanisms.
Some MSISDN can be blacklisted.
If failed transfers to a number are detected, and these failures are recurrent within a short time interval, then the number will be blocked.
As soon as 5 failures are detected over a period of 60 minutes, the MSISDN will be blacklisted and blocked.
Unblocking
A MSISDN is automatically unblocked after 7 days.