up to 128 simultaneous connections, the OCCB3 option module is required to increase the number of DSP channels. DSP channels are required to implement network transitions from TDM telephony to VoIP. OpenScape Business X3/X5/X8 has 8 DSP channels integrated on the mainboard. To expand DSP channels, the OCCB1 DSP module or the OCCB3 DSP module can be used as a plug-in module on the mainboard. In HiPath 3000, the HG1500 and possibly its PDM modules provided the DSP channels. The number of DSP channels required should be determined before migration.