One more trouble ( mod-openzap is configured like at previous letter ) : On running FS is done the following: freeswitch@opos8.altron.lan> load mod_openzap ... all OK ... configured span 1 & span 2 ... next is done: freeswitch@opos8.altron.lan> unload mod_openzap ... freeswitch@opos8.altron.lan> load mod_openzap In this case FreeSWITCH tries to configure span 3 & span 4 ( indtead the span 1 and span 2) - ERROR If we'll try repeat the same sequence : unload mod_openzap - load mod_openzap , then FreeSWITCH will configure spans 5 & 6. Why does it matters?