E&M Wink-start Acknowledgment

Unanswered Question
May 5th, 2008

Cisco 2851 should be sending 200ms of all 1's to acknowledge the completion of an incoming call on a T1 CAS circuit, but is only sending 0's.

Current setup:

2851XM, 12.4(9)T7, VWIC2-2MFT-T1 card

(1) 24-channel T1 CAS circuit, E&M wink-start

Callmanager 5.1 publisher and subscriber


Incoming calls drop at exactly two minutes, because the provider does not see the answer supervisor signal. Call actually completes, DTMF digits can be collected, voice conversation can be carried on, but the calling party phone doesn't see that the call is completed.

Pertinent config info:


network-clock-participate wic 0

network-clock-participate wic 1

network-clock-select 1 T1 0/0/0


controller T1 0/0/0

framing esf

linecode b8zs

no yellow generation

no yellow detection

ds0-group 1 timeslots 1-24 type e&m-wink-start


voice-port 0/0/0:1


Debug VPM Signal of non-answer supervision.

*May 5 22:51:22.610: htsp_process_event: [0/0/0:1(1), EM_ONHOOK, E_DSP_SIG_1100]em_onhook_offhook htsp_setup_ind

*May 5 22:51:22.610: [0/0/0:1(1)] get_local_station_id calling num= calling name= calling time=05/05 15:51 orig called=

*May 5 22:51:22.610: TGRM: reg_invoke_tgrm_accept_call(1, TGRM_CALL_VOICE, TGRM_DIRECTION_IN, 0, 0, 0, 1)

*May 5 22:51:22.610: TGRM: Calling vtsp_tsp_call_setup_ind().

*May 5 22:51:22.610: TGRM: reg_invoke_tgrm_call_update(0, 0, 0, 1, 1, TGRM_CALL_BUSY, TGRM_CALL_VOICE, TGRM_DIRECTION_IN)

*May 5 22:51:22.610: htsp_timer - 3000 msec

*May 5 22:51:22.614: htsp_validate_cap

*May 5 22:51:22.614: flex_modem_relay_supported:Modem Relay supported. flex_type=1

*May 5 22:51:22.614: htsp_process_event: [0/0/0:1(1), EM_WAIT_SETUP_ACK, E_HTSP_SETUP_ACK]em_wait_setup_ack_get_ack

*May 5 22:51:22.618: htsp_timer_stop interdigit timer cfgd to 3000

*May 5 22:51:22.618: htsp_timer2 - 172 msec

*May 5 22:51:22.622: htsp_process_event: [0/0/0:1(1), EM_WAIT_SETUP_ACK, E_HTSP_VOICE_CUT_THROUGH]em_wait_setup_ack_cut_thru

*May 5 22:51:22.622: htsp_call_bridged invoked

*May 5 22:51:22.626: flex_dsprm_forking_mixing_support:

*May 5 22:51:22.626: mars_flex_dsprm_current_codec_comp:DSP:0 FLEX Complexity Codec

*May 5 22:51:22.626: DSPWARE Version >= 3.0, actual is 8.4.7

*May 5 22:51:22.626: htsp_process_event: [0/0/0:1(1), EM_WAIT_SETUP_ACK, E_HTSP_VOICE_CUT_THROUGH]em_wait_setup_ack_cut_thruhtsp_connect: no_offhook 0 call_connected 0

*May 5 22:51:22.666: htsp_process_event: [0/0/0:1(1), EM_WAIT_SETUP_ACK, E_HTSP_CONNECT]em_wait_setup_ack_connect

*May 5 22:51:22.666: em_stop_timers

*May 5 22:51:22.666: htsp_timer_stop

*May 5 22:51:22.666: htsp_timer_stop2

*May 5 22:51:22.666: em_offhook (0)vnm_dsp_set_sig_state:[recEive and transMit0/0/0:1(1)] set signal state = 0x8em_onhook (201)vnm_dsp_set_sig_state:[recEive and transMit0/0/0:1(1)] set signal state = 0x0

I have this problem too.
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ivillegas Fri, 05/09/2008 - 05:58

On an incoming call the following will happen:

Network goes off-hook. A-bit = 1, B-bit =1

CPE sends wink. A-bit =1, B-bit =1 for 200ms. This only occurs when using wink-start or wink-start with wink acknowledgement. Ignore this step for immediate start.

Network sends DNIS information. This is done by sending inband tones which are decoded by the modem.

CPE sends a wink acknowledgement. A-bit =1, B-bit = 1 for 200ms. This only occurs for wink-start with wink acknowledgement. Ignore this step for immediate start or wink-start.

CPE goes off-hook when call is answered. A-bit =1, B-bit =1.

For outgoing call the same procedure above occurs. However, the 'network'

described above would be the 'cpe' and vice-versa. This is because

the signaling is symmetric.

During a Disconnect from the Network the following will occur:

1) Network goes 'on-hook'. A-bit = 0, B-bit = 0

2) CPE will go 'on-hook'. A-bit = 0, B-bit = 0

During a disconnect from the CPE, the above steps will be reversed.





estripoli Tue, 05/13/2008 - 13:47

Yep, I came across that same info before. But doesn't the debug indicate that the network is sending the 1's, but the router isn't (0ms of 1's, 201ms of 0's)?

Also, any hints on how to specifically configure wink-start with acknowledgement? Thanks!

amadathil Mon, 09/15/2008 - 14:23

Have you found a resolution to this problem. I am having similar issues with CAS T1 with E&M wink start. Looks like the answer supervision is not working correctly.

I am having this issue with few specific numbers where Serice provider does not see the answer supervisor signal. These are only for incomming calls where the call comes, and the router gets the address information and rings the internal ip phone, but when the phone goes off hook, the originator is still getting the ring back.

It looks like the originator is waiting for answer supervision signal, but its not getting it. So originator gets the ring back for ever.

Any one seen this before.

Can it be the IOS, am using 12.3


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