请教一个asterisk拨外地号码的问题

kover

现在搭建好asterisk语音网关了，拨打本地号码正常通话

但是拨打外地跨运营商的号码，就不通了，那个号码也没响铃
日志如下

Connected to Asterisk 18.11.2 currently running on OpenWrt (pid = 20621)
    -- Got SIP response 503 "Service Unavailable" back from 172.1.x.x:5060
    -- SIP/trunk_ims-00000000 is circuit-busy
  == Everyone is busy/congested at this time (1:0/1/0)
    -- Auto fallthrough, channel 'PJSIP/1001-00000000' status is 'CONGESTION'
[Jun 10 11:58:14] ERROR[21245]: res_pjsip_session.c:937 handle_incoming_sdp:  1001: Couldn't negotiate stream 0:audio-0:audio:sendrecv (nothing)
    -- Executing [013977123456@makecal:1] Dial("PJSIP/1001-00000001", "SIP/13977123456@trunk_ims,60,r") in new stack
  == Using SIP VIDEO CoS mark 6
  == Using SIP RTP CoS mark 5
    -- Called SIP/13977123456@trunk_ims
    -- SIP/trunk_ims-00000001 is making progress passing it to PJSIP/1001-00000001
    -- SIP/trunk_ims-00000001 redirecting info has changed, passing it to PJSIP/1001-00000001
    -- SIP/trunk_ims-00000001 is busy
  == Everyone is busy/congested at this time (1:1/0/0)
    -- Auto fallthrough, channel 'PJSIP/1001-00000001' status is 'BUSY'

有大佬知道问题出在哪吗，如何解决？
（按0拨外线，如果用电话机拨打外地号码前面加0，但是这个asterisk里面打13977123456，我这样按0013977123456，日志里面却把两个0都给消掉了）

lhn1324

建议装一个 sngrep 看看sip通讯的过程。