Short codes, also known as short numbers, are special telephone numbers, significantly shorter than full       telephone numbers, which can also be used to address SMS and MMS messages from mobile phones or fixed phones.                                                               
In South Africa, short codes are five digits in length and will start with either a "3" or "4". For example: 34001 or     42001. Each short code or short code range (a range will generally be 34000 to 34009) are assigned specific tariffs.                                                       

The tariff charges can range from R0.50 to R30.00 on mobile originated billing and from                                                     R0.50 to R50.00 using mobile terminated billing.                                                                                                                                                                                                    
Short codes are designed to be shorter to read out and easier to remember than normal                                                   telephone numbers. While similar to telephone numbers, they are, at a technological level,                                                  unique to each operator, although providers generally have agreements to avoid overlaps.                                                                                                                                                                                                      
Short codes are widely used for value-added services such as television voting, ordering                                                     ringtones, charity donations and mobile services. Messages sent to a short code can be                                                     billed at a higher rate than a standard SMS. For more information please visit                                                                     www.waspa.org.za and www.smscode.co.za

- Wikipedia