1

2

3

4

5

6

7

External ShortMessaging Entity

Short MessagingService Center

8

Home LocationRegister

Mobile SwitchingCenter

9

Public SwitchedTelephone Network

Visitor LocationRegister

10

Base Station

11

Paging Channel

SMS Delivery / Voice Call Establishment

Random AccessChannel

SMS Delivery / Voice Call Establishment

12

Standalone DedicatedControl Channel

SMS Delivery / Voice Call Establishment