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How to resolve FXO GroundStart outbound call failures

Resolution

Perform these procedures to resolve general GroudStart (GS) issues:

  1. The functionality of the GS line from the Central Office (CO) should be  verified first. Using a ButtSet or similar testing device, ground the ring. Lead and listen for dial tone to be returned from the CO.
  2. Once dial tone is heard, you should be able to dial digits to complete a voice call. If you cannot get dial tone from the CO, take this issue up with the provider.
  3. Once the GS line is verified, connect the VIC-2FXO, VIC2-2FXO, VIC2-4FXO, or NM-HDA Foreign Exchange Office (FXO) voice port to the GS line with the RJ-11 cabling. The easiest way to test outbound calls is to build a simple Plain Old Telephone Service (POTS) dial peer on the voice gateway, as shown:

    dial-peer voice X pots

    destination-pattern 9T

    port X/Y/Z

    By issuing the csim start hidden command, you can send calls to whichever real world E.164 number is desired to see if it is possible to correctly go off hook from the router to the Public Switched Telephone Network (PSTN), send digits, and complete a call to the proper destination phone. Modify the POTS dial-peer appropriately to account for long distance access codes and other prefixed digits as necessary.

    Issue the debug vpm all undebug vpm dsp command. Then issue the csim command to send an outbound call. Compare the debugs with this output for a successful FXOGS outbound call:

    *Mar 1 04:33:08.838: [1/1:1(1), FXOGS_ONHOOK, E_HTSP_SETUP_REQ] fxogs_onhook_setup[Foreign Exchange Office
    1/1:1(1)] set signal state = 0x0
    *Mar 1 04:33:08.838: htsp_timer - 10000 msec
    *Mar 1 04:33:09.214: htsp_dsp_message: SEND/RESP_SIG_STATUS: state=0x4 timestamp=40280 systime=1638921
    *Mar 1 04:33:09.218: [1/1:1(1), FXOGS_WAIT_TIP_GROUND, E_DSP_SIG_0100] fxogs_start_dial
    *Mar 1 04:33:09.218: htsp_timer_stop [Foreign Exchange Office 1/1:1(1)] set signal state = 0xC
    *Mar 1 04:33:09.218: htsp_timer - 1000 msec
    *Mar 1 04:33:10.218: [1/1:1(1), FXOGS_WAIT_DIAL_TONE, E_HTSP_EVENT_TIMER] fxogs_wait_dial_timer htsp_dial
    *Mar 1 04:33:12.226: [1/1:1(1), FXOGS_WAIT_DIAL_DONE, E_DSP_DIALING_DONE] fxogs_wait_dial_donehtsp_connect:
    no_offhook 0htsp_alert
    *Mar 1 04:33:12.226: [1/1:1(1), FXOGS_OFFHOOK, E_HTSP_CONNECT] fxogs_proc_voice
    *Mar 1 04:33:12.478: [1/1:1(1), FXOGS_OFFHOOK, E_HTSP_VOICE_CUT_THROUGH]
    *Mar 1 04:33:12.514: [1/1:1(1), FXOGS_OFFHOOK, E_HTSP_VOICE_CUT_THROUGH]
    *Mar 1 04:33:12.526: [1/1:1(1), FXOGS_OFFHOOK, E_HTSP_VOICE_CUT_THROUGH]
    #Call connects now and is answered.  No signaling is reported (no answer supervision for groundstart)
    #Call disconnected from VOIP leg below vdtl-2600-6d#htsp_release_req: cause 16, no_onhook 0
    *Mar 1 04:33:22.590: [1/1:1(1), FXOGS_OFFHOOK, E_HTSP_RELEASE_REQ] fxogs_offhook_release
    *Mar 1 04:33:22.590: htsp_timer_stop
    *Mar 1 04:33:22.590: htsp_timer_stop2 [Foreign Exchange Office 1/1:1(1)] set signal state = 0x4
    *Mar 1 04:33:22.590: htsp_timer - 2000 msec
    *Mar 1 04:33:22.778: htsp_dsp_message: SEND/RESP_SIG_STATUS: state=0xC timestamp=53840 systime=1640278
    *Mar 1 04:33:22.778: [1/1:1(1), FXOGS_WAIT_ONHOOK, E_DSP_SIG_1100] fxogs_waitonhook_onhook
    *Mar 1 04:33:22.778: htsp_timer_stop
    *Mar 1 04:33:22.778: htsp_timer - 2000 msec
    *Mar 1 04:33:22.782: vnm_dsprm_close_cleanup
    *Mar 1 04:33:24.778: [1/1:1(1), FXOGS_GUARD_OUT, E_HTSP_EVENT_TIMER]

    If the call rings the desired phone, the issue is resolved. If not, go to the next step.

  4. GS signaling is polarity-sensitive, so it is important that the Tip and Ring (T&R) leads on the RJ-11 line are properly connected between the demarc from the CO and the FXO port on the VIC-2FXO, VIC2-2FXO, VIC2-4FXO, or NM-HDA FXO equipment. If the polarity is reversed from what it needs to be, inbound calls from the CO to the router work, but outbound call attempts from the router to the CO fail 100 percent of the time. Therefore, a check on the T&R polarity is one of the first things which should be tested.

    The easiest way to quickly reverse the polarity on an RJ-11 line is to use an RJ-45 cable extender and a short span of two-wire RJ-11 crossover cable  to insert inline between the existing cabling and the voice port. Such a short crossover RJ-11 cable can either be crimped by the tester, or it can be commonly retrieved from the collection of accessories from store-bought analog phones, which often come with such a cable. Two-wire RJ-11 cabling is preferred for both testing and production connections to Foreign Exchange Station (FXS) and FXO voice ports, with just the conductors on pins two and three connected.

    Ensure that the chassis ground reference and the electrical ground reference that the CO provides for the GS line are the same.

  5. If things continue to fail, verify that the VIC-2FXO, VIC2-2FXO, VIC2-4FXO, or NM-HDA FXO equipment is functioning properly. The easiest empirical way to do this is to connect the FXO port to a known good FXS port like an VIC-2FXS, VIC2-2FXS, VIC-2DID (in FXS mode), VIC-4FXS/DID (in FXS mode) or NM-HDA FXS port on another (or same) Cisco voice gateway. In this case, use a a straight-through two-wire RJ-11 connection.

    The aim of connecting the FXOGS voice port to an FXSGS voice port is to verify that one voice gateway can signal the other over the connection and draw dial tone from the peer gateway. This is a complete testing scenario:

          (x888)PhnA---FXSLS[ RtrA ]FXOGS====FXSGS[ RtrB ]FXSLS---PhnB(x999)

                      (1/0/0)      (2/0/0)  (2/0/0)      (1/0/0)

                         RtrA                            RtrB

              !                               !  

              voice-port 1/0/0                voice-port 1/0/0

              !                               !

              voice-port 2/0/0                voice-port 2/0/0

               signal GroundStart              signal GroundStart

              !                               !

              dial-peer voice 888 pots        dial-peer voice 888 pots

               destination-pattern 888         destination-pattern 888

               port 1/0/0                      port 2/0/0

              !                               !

              dial-peer voice 999 pots        dial-peer voice 999 pots

               destination-pattern 999         destination-pattern 999

               port 2/0/0                      port 1/0/0

              !                               !

    In this scenario, a user can pick up an analog phone to get dial tone from the local router, dial the far-end extension to go off hook on the GS line, hear dial tone from the peer gateway, then dial the far-end extension once again to complete the call to the far-end phone. If this works correctly in both directions, the FXO voice port is functioning as expected. Make sure to check for two-way audio.

  6. To further verify the Cisco FXO equipment, determine if there is a Digital Signal Processor (DSP) firmware (DSPware) defect involved. Issue the show voice dsp command (or other appropriate command if the DSPware is Flexi) to determine the version level of the DSPware for the FXO ports. Contact the Cisco Technical Support website for further assistance.
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