Had this same issue about a week ago with a UK number. All domestic and other international calls go through just fine. Here’s a snippet from the debug log:
[2016-12-06 12:19:17] VERBOSE[10634][C-000001da] app_dial.c: Called SIP/flowroute/0116788282425
[2016-12-06 12:19:17] VERBOSE[10636][C-000001da] app_mixmonitor.c: Begin MixMonitor Recording SIP/403-0000005a
[2016-12-06 12:19:17] DEBUG[10636][C-000001da] audiohook.c: Read factory 0x7f7d48298b68 and write factory 0x7f7d482995a8 both fail to provide 160 samples
[2016-12-06 12:19:17] DEBUG[20214][C-000001da] chan_sip.c: (Provisional) Stopping retransmission (but retaining packet) on '[email protected]' Request 102: Found
[2016-12-06 12:19:17] DEBUG[20214][C-000001da] chan_sip.c: Acked pending invite 102
[2016-12-06 12:19:17] DEBUG[20214][C-000001da] chan_sip.c: Stopping retransmission on '[email protected]' of Request 102: Match Found
[2016-12-06 12:19:17] DEBUG[20214][C-000001da] chan_sip.c: ** Our capability: (alaw|g729|ulaw|g722|g726) Video flag: False Text flag: False
[2016-12-06 12:19:17] DEBUG[20214][C-000001da] chan_sip.c: ** Our prefcodec: (alaw)
[2016-12-06 12:19:17] DEBUG[20214][C-000001da] chan_sip.c: (Provisional) Stopping retransmission (but retaining packet) on '[email protected]' Request 103: Found
[2016-12-06 12:19:18] DEBUG[20214][C-000001da] chan_sip.c: Acked pending invite 103
[2016-12-06 12:19:18] DEBUG[20214][C-000001da] chan_sip.c: Stopping retransmission on '[email protected]' of Request 103: Match Found
[2016-12-06 12:19:18] WARNING[20214][C-000001da] chan_sip.c: Received response: "Forbidden" from '"xxxxxxxxxxxx" <sip:[email protected]>;tag=as5e486071'
[2016-12-06 12:19:18] DEBUG[10634][C-000001da] channel.c: Hanging up channel 'SIP/flowroute-0000005b'
[2016-12-06 12:19:18] DEBUG[10634][C-000001da] chan_sip.c: Hangup call SIP/flowroute-0000005b, SIP callid [email protected]
[2016-12-06 12:19:18] DEBUG[10634][C-000001da] res_rtp_asterisk.c: Setting RTCP address on RTP instance '0x7f7d488edf78'
[2016-12-06 12:19:18] VERBOSE[10634][C-000001da] app_dial.c: Everyone is busy/congested at this time (1:0/0/1)
I’ve emailed Flowroute with the number being dialed to see if they’d reject it for some reason. Anything else I can try in the meantime?
Thanks.