Definition
A grey route delivers A2P SMS to an operator without the operator’s commercial agreement, for example through SIM banks or P2P interconnects, avoiding the A2P termination charge.
Grey routes look cheaper because they skip the operator’s A2P rate. Common methods include SIM boxes sending business messages from consumer SIMs and passing A2P traffic as P2P over international interconnects.
For the sender, the downsides are real: sender IDs are often replaced with random numbers, delivery receipts may be fake, throughput is unstable, and operators block the route without warning once they detect it.
Operators fight grey routes with SMS firewalls and SIM box detection. Regulators in many countries, including in the GCC, expect A2P traffic to travel over sanctioned routes.
Signs you are on a grey route: unusually low prices, sender ID not preserved, delivery rates that vary from day to day and receipts that report delivery to numbers that are switched off.