DDS link speeds are generally available from 2.4Kbits up to 2Mbits although for Internet use only speeds of 9600 and above are useful. Long distance connections, for example between two cities, really only have two options. Either a DDS circuit, ie one of the DDS variants, OR a frame relay service. An alternative to DDS is Frame Relay , where each end of the link plugs into a switched network. The customer can then purchase a bandwidth amount for the link to the network at as many locations where link access will be required.
Frame relay can be very cost competitive when compared to the dedicated types of DDS circuit.
However, experience in NZ has shown that the overall throughput of a frame relay link does not come up to the performance of a DDS circuit even though an CIR has been purchased. There would appear to be times when the FR Network is either overloaded generally or at specific points. Within the major cities in New Zealand there are lower cost options for Internet connections. The 9k6 and lower speeds are really not suitable for an Internet connection as they are simply too low throughput. Lower cost is a relative term but lower it is when compared to standard DDS charges.