Fax transmission error

richard.priest · ‎10-23-2018

Hi,

I've got an issue with a fax connected to our CUCM 10.5 instance via a VG202.

Whenever anyone tries to send a fax to the device it errors with a fax transmission error.

If I attach an analogue phone, calls can be made normally.

If I call the fax number with the fax attached I hear the typical protocol synchronization noises you hear from a fax machine.

If I call the fax whilst running debug sccp events I get the following error report

Oct 23 13:47:03.411: sccp_send_onhook_v1
Oct 23 13:47:33.216: sccpapp_process_timer_events: appl_type 4, experied_timer 3, xlated_eve 11, state 6
Oct 23 13:47:33.216: sccp_handle_keep_alive_timeout: Handle keepalive timeout for appl_type 4, state 6
Oct 23 13:47:33.216: sccp_appl_service_start_timer: Start timer type 3 with time_out 30000ms
Oct 23 13:47:42.621: sccp_spi_dev_off_hook: enqueue spi evt SCCP_SPI_DEV_OFF_HOOK, reg_name=AN1FCAC59438000
Oct 23 13:47:42.621: sccp_send_offhook_v1
Oct 23 13:47:42.649: sccp_dcapi_extract_and_validate_srtp_context
Oct 23 13:47:42.649: sccp_spi_orc_ack: enqueue spi evt SCCP_SPI_MEDIA_ORC_ACK, reg_name=AN1FCAC59438000
Oct 23 13:47:42.653: sccp_dcapi_extract_and_validate_srtp_context
Oct 23 13:48:03.218: sccpapp_process_timer_events: appl_type 4, experied_timer 3, xlated_eve 11, state 6
Oct 23 13:48:03.218: sccp_handle_keep_alive_timeout: Handle keepalive timeout for appl_type 4, state 6
Oct 23 13:48:03.218: sccp_appl_service_start_timer: Start timer type 3 with time_out 30000ms
Oct 23 13:48:26.847: sccp_spi_dev_on_hook: enqueue spi evt SCCP_SPI_DEV_ON_HOOK, reg_name=AN1FCAC59438000
Oct 23 13:48:26.847: sccp_send_onhook_v1
Oct 23 13:48:33.219: sccpapp_process_timer_events: appl_type 4, experied_timer 3, xlated_eve 11, state 6
Oct 23 13:48:33.219: sccp_handle_keep_alive_timeout: Handle keepalive timeout for appl_type 4, state 6
Oct 23 13:48:33.219: sccp_appl_service_start_timer: Start timer type 3 with time_out 30000ms
Oct 23 13:49:03.221: sccpapp_process_timer_events: appl_type 4, experied_timer 3, xlated_eve 11, state 6
Oct 23 13:49:03.221: sccp_handle_keep_alive_timeout: Handle keepalive timeout for appl_type 4, state 6
Oct 23 13:49:03.221: sccp_appl_service_start_timer: Start timer type 3 with time_out 30000ms
Oct 23 13:49:33.222: sccpapp_process_timer_events: appl_type 4, experied_timer 3, xlated_eve 11, state 6
Oct 23 13:49:33.222: sccp_handle_keep_alive_timeout: Handle keepalive timeout for appl_type 4, state 6
Oct 23 13:49:33.222: sccp_appl_service_start_timer: Start timer type 3 with time_out 30000ms
Oct 23 13:50:03.224: sccpapp_process_timer_events: appl_type 4, experied_timer 3, xlated_eve 11, state 6
Oct 23 13:50:03.224: sccp_handle_keep_alive_timeout: Handle keepalive timeout for appl_type 4, state 6
Oct 23 13:50:03.224: sccp_appl_service_start_timer: Start timer type 3 with time_out 30000ms
Oct 23 13:50:33.225: sccpapp_process_timer_events: appl_type 4, experied_timer 3, xlated_eve 11, state 6
Oct 23 13:50:33.225: sccp_handle_keep_alive_timeout: Handle keepalive timeout for appl_type 4, state 6
Oct 23 13:50:33.225: sccp_appl_service_start_timer: Start timer type 3 with time_out 30000ms
Oct 23 13:51:03.226: sccpapp_process_timer_events: appl_type 4, experied_timer 3, xlated_eve 11, state 6
Oct 23 13:51:03.226: sccp_handle_keep_alive_timeout: Handle keepalive timeout for appl_type 4, state 6
Oct 23 13:51:03.226: sccp_appl_service_start_timer: Start timer type 3 with time_out 30000ms
Oct 23 13:51:33.227: sccpapp_process_timer_events: appl_type 4, experied_timer 3, xlated_eve 11, state 6
Oct 23 13:51:33.227: sccp_handle_keep_alive_timeout: Handle keepalive timeout for appl_type 4, state 6
Oct 23 13:51:33.227: sccp_appl_service_start_timer: Start timer type 3 with time_out 30000ms
Oct 23 13:52:03.229: sccpapp_process_timer_events: appl_type 4, experied_timer 3, xlated_eve 11, state 6
Oct 23 13:52:03.229: sccp_handle_keep_alive_timeout: Handle keepalive timeout for appl_type 4, state 6
Oct 23 13:52:03.229: sccp_appl_service_start_timer: Start timer type 3 with time_out 30000ms
Oct 23 13:52:33.230: sccpapp_process_timer_events: appl_type 4, experied_timer 3, xlated_eve 11, state 6
Oct 23 13:52:33.230: sccp_handle_keep_alive_timeout: Handle keepalive timeout for appl_type 4, state 6
Oct 23 13:52:33.230: sccp_appl_service_start_timer: Start timer type 3 with time_out 30000ms
Oct 23 13:53:03.231: sccpapp_process_timer_events: appl_type 4, experied_timer 3, xlated_eve 11, state 6
Oct 23 13:53:03.231: sccp_handle_keep_alive_timeout: Handle keepalive timeout for appl_type 4, state 6
Oct 23 13:53:03.231: sccp_appl_service_start_timer: Start timer type 3 with time_out 30000ms

My knowledge debugging CUCM issues is pretty limited so I appreciate any advise that can be offered!

Cheers

Brandon Buffin · ‎10-23-2018

Fax machines are very susceptible to any errors on the line. Check your connection (PRI?) for any errors. Also, try reducing the negotiated speed on the fax machine down to 14400 or 9600.

Brandon

richard.priest · ‎10-23-2018

Apologies if this is a naive question, how do I check the PRI for errors?

Tried adjusting the fax, there is zero config available on the fax to reduce the speed. I do know it's a superG3 device so runs at 33600bps.

Brandon Buffin · ‎10-23-2018

"show controller t1" on the gateway that terminates your PRI. If no errors, find a fax machine that will allow you to adjust the speed and test. That would at least narrow down the problem.

Brandon

Jonathan Schulenberg · ‎10-28-2018

Is T.38 fax relay properly configured on the VG and PSTN gateways?

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/voice/fax/configuration/15-mt/vf-15-mt-book/Configuring_T_38_Fax_Relay.html

https://www.cisco.com/c/en/us/support/docs/voice-unified-communications/unified-border-element/115742-fax-modem-call-flows-00.html

Edit: I just noticed that you mentioned a SCCP debug. This will require you to use NSE-based T.38 switchover. The far more common approach (and only option supported by Telcos over SIP if you replace your PRI) is protocol-based T.38 switchover. Unless your VG requires supplemental feature codes (eg park, pickup), it would be better to configure it using MGCP.