upgrading from zaptel to dahdi, with a TDM400P: Is /etc/dahdi/system.conf the same as /etc/zaptel.conf? As I read the system.conf.sample, no echo canceller need be specified if there's a hardware ec. Can I just rename zaptel.conf? What about zapata.conf? Is this just renamed /etc/asterisk/chan_dahdi.conf? Or zapata-channels.conf? Or just left alone? sean