ES 201 912 is the European Telecommunications Standards Institute (ETSI) approved standard that allows the sending and receiving of Short Message Service (SMS) messages on PSTN/ISDN networks.
Protocol Type 1
Protocol Type 1 allows for a standard message size of 160 characters. Multiple messages may be combined. Protocol Type 1 is compliant with GSM SMS services and can be used with mobile devices.
This protocol, sometimes with minor variations, is used in the UK, Germany, France and other countries.
Protocol Type 2
Protocol Type 2 is a new design. It allows for messages up to 640 characters. Protocol Type 2 is designed primarily for residential fixed networks.
Spain and Italy are the only countries yet to implement the Type 2 protocol consequently implementations of the Type 2 protocol are very scarce on the ground.
Hardware for both protocol types is almost identical. The differences between the two protocols are found mainly in the higher protocol layers.
Data is transmitted in a traditional voice-band call, using 1200 Baud FSK modulation.
Any terminal hardware must be capable of sending and receiving 1200 Baud FSK according to ETSI standard for off hook data transmission.