The beauty with Asterisk is you start with the software and you add the hardware around it. Given these

Extending Open Source PBX For Scalable Media Gateways Presented by: Nenad Corbic, B.Eng Chief Software EngineerSoftware Manager Sangoma Technologies2-Jun-08 / 1Limitations of Current Soft PBX Architecture• Monolithic/Single Server Architecture. • TDM Bottleneck (Zaptel/TDM Hardware)• Software Echo Cancellation & DTMF & D-Chan HDLC• Software Codec (g729)• Kernel / User Space Context Penalty• TDM Clustering Solutions limited and hard to configure• Customer need for 16 x E1 =~ 500 calls or greater !2-Jun-08 / 2Current Asterisk Open Source PBX ModelAsterisk PBXlibprichan_zap.sochan_sip.soIPIPZAPTEL Kernel SpaceTDM TDM T1/E1T1/E1Drivers/Hardware(Sangoma/Digium)2-Jun-08 / 3Hardware Interrupt Penalty: SW EC & DTMF Asterisk PBXsipiaxIPchan_zap.so / libpri/dev/zap/ 0 1 2 3 4 5 6 7 8 9 10 … 245 246… 500... 600Kernell ZAPTEL SpaceSpaceSoft EC and DCHAN HDLChw_isr() 1000 isr / sec * spans1ms 1ms 1ms 1ms 1ms1ms 1ms 1ms 1ms8byt 8byt 8byt 8byt 8byt8byt 8byt 8byt 8bytTDM Drivers/Hardware (Sangoma/Digium)T1/E1/BRI/Analog2-Jun-08 / 4HW Optimizations: EC & DTMF & DCHAN HDLC Asterisk PBX sipiaxIPchan_zap.so / libpri/dev/zap/ 0 1 2 3 4 5 6 7 8 9 10 … 245 246… 500... 600Kernell SpaceeZAPTEL hw_isr() 100 isr / sec10ms 10ms 10ms 10ms 10ms 10ms 10ms 10ms80byt 80byt 80byt 80byt 80byt 80byt 80byt 80bytHardware Echo Cancellellation & DTMF & DCHAN HDLCTDM Drivers/Hardware (Sangoma/Digium)T1/E1/BRI/Analog2-Jun-08 ...