передически отпадывает телефон

есть 2 экстеншена. 213 и 214. с 213 всегда звонки уходят. а вот приходить иногда не приходя, телефон говорит что номер занят, хотя никто не разговаривает и DND отключен

[2013-06-25 18:23:02]     -- Executing [213@office:1] Set("SIP/214-00000237", "NUMBER=213") in new stack
[2013-06-25 18:23:02]     -- Executing [213@office:2] Gosub("SIP/214-00000237", "settings1,1") in new stack
[2013-06-25 18:23:02]     -- Executing [settings1@office:1] Set("SIP/214-00000237", "TRANSFER_CONTEXT=office") in new stack
[2013-06-25 18:23:02]     -- Executing [settings1@office:2] Set("SIP/214-00000237", "CDR(accountcode)=local-office") in new stack
[2013-06-25 18:23:02]     -- Executing [settings1@office:3] Return("SIP/214-00000237", "") in new stack
[2013-06-25 18:23:02]     -- Executing [213@office:3] Gosub("SIP/214-00000237", "record,local_direct,1") in new stack
[2013-06-25 18:23:02]     -- Executing [local_direct@record:1] GotoIf("SIP/214-00000237", "1?2:4") in new stack
[2013-06-25 18:23:02]     -- Goto (record,local_direct,2)
[2013-06-25 18:23:02]     -- Executing [local_direct@record:2] Set("SIP/214-00000237", "MONITOR_FILENAME=1372162982.643_lo_214_213") in new stack
[2013-06-25 18:23:02]     -- Executing [local_direct@record:3] Monitor("SIP/214-00000237", "wav,1372162982.643_lo_214_213,mb") in new stack
[2013-06-25 18:23:02]     -- Executing [local_direct@record:4] NoOp("SIP/214-00000237", "Finish if_record_7") in new stack
[2013-06-25 18:23:02]     -- Executing [local_direct@record:5] GotoIf("SIP/214-00000237", "0?6:7") in new stack
[2013-06-25 18:23:02]     -- Goto (record,local_direct,7)
[2013-06-25 18:23:02]     -- Executing [local_direct@record:7] NoOp("SIP/214-00000237", "Finish if_record_8") in new stack
[2013-06-25 18:23:02]     -- Executing [local_direct@record:8] Return("SIP/214-00000237", "") in new stack
[2013-06-25 18:23:02]     -- Executing [213@office:4] Dial("SIP/214-00000237", "SIP/213,,tT") in new stack
[2013-06-25 18:23:02]     -- Called 213
[2013-06-25 18:23:02]     -- Got SIP response 486 "Busy Here" back from 192.168.3.216
[2013-06-25 18:23:02]     -- SIP/213-00000238 is busy
[2013-06-25 18:23:02]   == Everyone is busy/congested at this time (1:1/0/0)
[2013-06-25 18:23:02]     -- Executing [213@office:5] Hangup("SIP/214-00000237", "") in new stack
[2013-06-25 18:23:02]   == Spawn extension (office, 213, 5) exited non-zero on 'SIP/214-00000237'
[2013-06-25 18:23:02]     -- Executing [h@office:1] NoOp("SIP/214-00000237", "H=BUSY local-office 213 0") in new stack