Why are messages to numbers beginning with +879 trashed or blacklisted?
The numbers to which these messages are sent are all +879 numbers, which are temporary numbers (France Alias) allocated by operators for a short period of time for Premium services in France. Once this period has elapsed any messages sent to those numbers will be trashed. This is to aid the prevention of spam messages being sent to end users and so these numbers must not be used to send MT messages to end-users.
When sending a MO to a premium shortcode in France, you do not get the clear MSISDN but an alias. Internally at Digital Interconnect it is identified with a MSISDN starting with +879 followed by a single digit number which represents the ID of the Operator:
1 - for Bouygues France
2 - for SFR France
3 - for Orange France
4 - for Free Mobile France (Implementation of RS services is not finished for this operator)