Не идут звонки по IAX

Есть 2 сервера Asterisk 1.6.2.24

Сервер А [iax.conf]:

[kazan] type=friend host=XXX.XXX.XXX.XXX auth=MD5 trunk=yes secret=welcome context=kazan 

Сервер Б [iax.conf]:

[volgograd] type=friend auth=MD5 host=XXX.XXX.XXX.XXX trunk=yes secret=welcome context=volgograd 

Звонок с Сервера А на Сервер Б проходит нормально, а вот обратно с Сервера Б на сервер А вообще не идет. В чем может быть причина?

Логи на Сервер А [iax debug]:

Rx-Frame Retry[ No] -- OSeqno: 000 ISeqno: 000 Type: IAX Subclass: NEW Timestamp: 00014ms SCall: 00977 DCall: 00000 [XXX.XXX.XXX.XXX:4569] VERSION : 2 CALLED NUMBER : 4777 CODEC_PREFS : (gsm) CALLING NUMBER : 8432XXXXXXX CALLING PRESNTN : 3 CALLING TYPEOFN : 33 CALLING TRANSIT : 0 CALLING NAME : LANGUAGE : en USERNAME : kazan FORMAT : 2 CAPABILITY : 2 ADSICPE : 2 DATE TIME : 2012-10-26 14:51:48 Rx-Frame Retry[Yes] -- OSeqno: 000 ISeqno: 000 Type: IAX Subclass: NEW Timestamp: 00014ms SCall: 00977 DCall: 00000 [XXX.XXX.XXX.XXX:4569] VERSION : 2 CALLED NUMBER : 4777 CODEC_PREFS : (gsm) CALLING NUMBER : 8432XXXXXXX CALLING PRESNTN : 3 CALLING TYPEOFN : 33 CALLING TRANSIT : 0 CALLING NAME : LANGUAGE : en USERNAME : kazan FORMAT : 2 CAPABILITY : 2 ADSICPE : 2 DATE TIME : 2012-10-26 14:51:48 Rx-Frame Retry[ No] -- OSeqno: 001 ISeqno: 000 Type: IAX Subclass: HANGUP Timestamp: 04015ms SCall: 00977 DCall: 00000 [XXX.XXX.XXX.XXX:4569] CAUSE CODE : 0 Rx-Frame Retry[Yes] -- OSeqno: 001 ISeqno: 000 Type: IAX Subclass: HANGUP Timestamp: 04015ms SCall: 00977 DCall: 00000 [XXX.XXX.XXX.XXX:4569] CAUSE CODE : 0 Rx-Frame Retry[Yes] -- OSeqno: 000 ISeqno: 000 Type: IAX Subclass: NEW Timestamp: 00014ms SCall: 00977 DCall: 00000 [XXX.XXX.XXX.XXX:4569] VERSION : 2 CALLED NUMBER : 4777 CODEC_PREFS : (gsm) CALLING NUMBER : 8432XXXXXXX CALLING PRESNTN : 3 CALLING TYPEOFN : 33 CALLING TRANSIT : 0 CALLING NAME : LANGUAGE : en USERNAME : kazan FORMAT : 2 CAPABILITY : 2 ADSICPE : 2 DATE TIME : 2012-10-26 14:51:48 

Сервер Б [iax debug]:

Tx-Frame Retry[000] -- OSeqno: 000 ISeqno: 000 Type: IAX Subclass: NEW Timestamp: 00014ms SCall: 03512 DCall: 00000 [XXX.XXX.XXX.XXX:4569] VERSION : 2 CALLED NUMBER : 4777 CODEC_PREFS : (gsm) CALLING NUMBER : 8432XXXXXXX CALLING PRESNTN : 3 CALLING TYPEOFN : 33 CALLING TRANSIT : 0 CALLING NAME : LANGUAGE : en USERNAME : kazan FORMAT : 2 CAPABILITY : 2 ADSICPE : 2 DATE TIME : 2012-10-26 14:54:16 Rx-Frame Retry[Yes] -- OSeqno: 000 ISeqno: 001 Type: IAX Subclass: CTOKEN Timestamp: 00014ms SCall: 00001 DCall: 03512 [XXX.XXX.XXX.XXX:4569] Unknown IE 054 : Present Tx-Frame Retry[001] -- OSeqno: 000 ISeqno: 000 Type: IAX Subclass: NEW Timestamp: 00014ms SCall: 03512 DCall: 00000 [XXX.XXX.XXX.XXX:4569] VERSION : 2 CALLED NUMBER : 4777 CODEC_PREFS : (gsm) CALLING NUMBER : 8432XXXXXXX CALLING PRESNTN : 3 CALLING TYPEOFN : 33 CALLING TRANSIT : 0 CALLING NAME : LANGUAGE : en USERNAME : kazan FORMAT : 2 CAPABILITY : 2 ADSICPE : 2 DATE TIME : 2012-10-26 14:54:16 Rx-Frame Retry[Yes] -- OSeqno: 000 ISeqno: 001 Type: IAX Subclass: CTOKEN Timestamp: 00014ms SCall: 00001 DCall: 03512 [XXX.XXX.XXX.XXX:4569] Unknown IE 054 : Present Tx-Frame Retry[000] -- OSeqno: 001 ISeqno: 000 Type: IAX Subclass: HANGUP Timestamp: 04015ms SCall: 03512 DCall: 00000 [XXX.XXX.XXX.XXX:4569] CAUSE CODE : 0 Tx-Frame Retry[001] -- OSeqno: 001 ISeqno: 000 Type: IAX Subclass: HANGUP Timestamp: 04015ms SCall: 03512 DCall: 00000 [XXX.XXX.XXX.XXX:4569] CAUSE CODE : 0 Tx-Frame Retry[002] -- OSeqno: 000 ISeqno: 000 Type: IAX Subclass: NEW Timestamp: 00014ms SCall: 03512 DCall: 00000 [XXX.XXX.XXX.XXX:4569] VERSION : 2 CALLED NUMBER : 4777 CODEC_PREFS : (gsm) CALLING NUMBER : 8432XXXXXXX CALLING PRESNTN : 3 CALLING TYPEOFN : 33 CALLING TRANSIT : 0 CALLING NAME : LANGUAGE : en USERNAME : kazan FORMAT : 2 CAPABILITY : 2 ADSICPE : 2 DATE TIME : 2012-10-26 14:54:16 Rx-Frame Retry[Yes] -- OSeqno: 000 ISeqno: 001 Type: IAX Subclass: CTOKEN Timestamp: 00014ms SCall: 00001 DCall: 03512 [XXX.XXX.XXX.XXX:4569] Unknown IE 054 : Present -- Accepting call from '843XXXXXXX' to '4777' on channel 0/23, span 1 -- Executing [4777@from_ats:1] Dial("DAHDI/23-1", "IAX2/kazan:welcome@XXX.XXX.XXX.XXX:4569/4777,15,t") in new stack -- Called kazan:welcome@XXX.XXX.XXX.XXX:4569/4777 [Oct 26 14:54:21] NOTICE[1664]: chan_iax2.c:4435 __auto_congest: Auto-congesting call due to slow response -- IAX2/10.0.0.11:4569-3512 is circuit-busy -- Hungup 'IAX2/XXX.XXX.XXX.XXX:4569-3512' == Everyone is busy/congested at this time (1:0/1/0) -- Executing [4777@from_ats:2] Hangup("DAHDI/23-1", "") in new stack == Spawn extension (from_ats, 4777, 2) exited non-zero on 'DAHDI/23-1' -- Hungup 'DAHDI/23-1'