Adopted by the 3GPP in 2007, Home Routing was devised to enable mobile networks to offer a full range of advanced services on both inbound and outbound SMS, giving more utility to phone users and enabling operators to generate additional revenue.
This inconsistency arose from the fact that SMS was conceived as a voicemail alert system, not a person-to-person messaging system, and it put SMS out of step with most other forms of communication including voice telephony, email and MMS where the home entity has responsibility for the management of both inbound and outbound traffic.
In 2006 UK mobile operator Vodafone argued before the 3GPP[1] that by effectively putting a large percentage of SMS traffic outside the direct control of the receiving network, the original GSM specification prevented operators from generating new revenue by offering certain types of value-added SMS services.
Home Routing uses the recipient network Home Location Register (HLR) to change the flow of inbound off-net messages, directing them to an SMS router, rather than straight to target handsets.
There, advanced services such as divert, copy, archiving and anti-spam can be applied before messages are delivered.