Foreign mobile network operators deploy deep packet inspection on international SS7 links; ensure your traffic routes through legitimate, authorized A2P gateways.
When sending messages to international users, cheap aggregators often attempt to exploit low-cost Person-to-Person (P2P) international roaming channels. Foreign telecom operators deploy strict SMS firewalls to block this unauthorized commercial traffic.
1 How International SMS Firewalls Operate
International carrier firewalls inspect Global Title (GT) origin addresses, SCCP calling party addresses, and SMPP submit_sm headers. Traffic matching commercial patterns sent over P2P links is dropped with zero delivery receipt confirmation.
Frequently Asked Questions • Carrier Spam Filters & Deliverability
White routes have direct bilateral agreements with terminating carriers and guarantee delivery. Gray routes exploit unauthorized signaling loopholes and suffer high drop rates.