Сделал как Вы сказали, теперь настройки интерфейса выглядят так:

interface Serial3/0:15
no ip address
encapsulation hdlc
isdn switch-type primary-net5
isdn incoming-voice modem
isdn send-alerting
isdn negotiate-bchan
isdn sending-complete
no cdp enable
end

Однако, звонки по-прежнему зависают. Ниже привожу детальную информацию по "зависшему" и нормальному звонку. У зависшего звонка наблюдаю параметр "Conference ID: -1", у нормального звонка: "Conference ID: 257". МОжет проблема в этом?

"зависший" звонок:

voip_gate_test1#show voice dsmp stream leg 481

Stream information:: stream=7159
Type: TDM, Direction: OUTPUT
Fax/Modem Type: voice
Xmit Function: 0x00000000
Xmit function is Enabled
Call ID: 481, Conference ID: -1

Session information:: session=0x67756ECC dsp_intf=0x64227C00 dsp_name=1/2:1

connections=0 streams=4 (7160 7159 7158 7157 )
current state S_DSMP_VC_RUNNING current container simple_voice_container
State Transitions: timestamp (container, state) -- event -> (container, state)
1279.188 (simple_voice_container, CNFSM_CONTAINER_STATE) -- E_DSMP_DSP_DTMF_DIGIT_BEGIN -> (simple_voice_container, CNFSM_NO_STATE_CHANGE)
1279.320 (simple_voice_container, CNFSM_CONTAINER_STATE) -- E_DSMP_DSP_DTMF_DIGIT_END -> (simple_voice_container, CNFSM_NO_STATE_CHANGE)
1282.760 (simple_voice_container, CNFSM_CONTAINER_STATE) -- E_DSMP_DSP_DTMF_DIGIT_BEGIN -> (simple_voice_container, CNFSM_NO_STATE_CHANGE)
1282.892 (simple_voice_container, CNFSM_CONTAINER_STATE) -- E_DSMP_DSP_DTMF_DIGIT_END -> (simple_voice_container, CNFSM_NO_STATE_CHANGE)
1284.052 (simple_voice_container, CNFSM_CONTAINER_STATE) -- E_DSMP_DSP_DTMF_DIGIT_BEGIN -> (simple_voice_container, CNFSM_NO_STATE_CHANGE)
1284.184 (simple_voice_container, CNFSM_CONTAINER_STATE) -- E_DSMP_DSP_DTMF_DIGIT_END -> (simple_voice_container, CNFSM_NO_STATE_CHANGE)
1286.744 (simple_voice_container, CNFSM_CONTAINER_STATE) -- E_DSMP_DSP_DTMF_DIGIT_BEGIN -> (simple_voice_container, CNFSM_NO_STATE_CHANGE)
1286.876 (simple_voice_container, CNFSM_CONTAINER_STATE) -- E_DSMP_DSP_DTMF_DIGIT_END -> (simple_voice_container, CNFSM_NO_STATE_CHANGE)
1287.088 (simple_voice_container, CNFSM_CONTAINER_STATE) -- E_DSMP_DSP_DTMF_DIGIT_BEGIN -> (simple_voice_container, CNFSM_NO_STATE_CHANGE)
1287.220 (simple_voice_container, CNFSM_CONTAINER_STATE) -- E_DSMP_DSP_DTMF_DIGIT_END -> (simple_voice_container, CNFSM_NO_STATE_CHANGE)
1288.020 (simple_voice_container, CNFSM_CONTAINER_STATE) -- E_DSMP_DSP_DTMF_DIGIT_BEGIN -> (simple_voice_container, CNFSM_NO_STATE_CHANGE)
1288.152 (simple_voice_container, CNFSM_CONTAINER_STATE) -- E_DSMP_DSP_DTMF_DIGIT_END -> (simple_voice_container, CNFSM_NO_STATE_CHANGE)
1288.356 (rsc_running_container, CNFSM_CONTAINER_STATE) -- E_DSMP_CC_MODIFY_REQ -> (rsc_running_container, S_DSMP_MODIFY_CAPS_SAVED)
1288.356 (rsc_running_container, S_DSMP_MODIFY_CAPS_SAVED) -- CNFSM_LAMBDA_EVENT -> (rsc_running_container, CNFSM_CONTAINER_STATE)
1288.356 (rsc_running_container, CNFSM_CONTAINER_STATE) -- E_DSMP_CC_CONNECT_REQ -> (simple_voice_container, S_DSMP_VC_RUNNING)
1297.012 (rsc_running_container, CNFSM_CONTAINER_STATE) -- E_DSMP_CC_DISCONNECT -> (rsc_running_container, CNFSM_NO_STATE_CHANGE)
1297.012 (rsc_running_container, CNFSM_CONTAINER_STATE) -- E_DSMP_CC_MODIFY_REQ -> (rsc_running_container, S_DSMP_MODIFY_CAPS_SAVED)
1297.012 (rsc_running_container, S_DSMP_MODIFY_CAPS_SAVED) -- CNFSM_LAMBDA_EVENT -> (rsc_running_container, CNFSM_CONTAINER_STATE)
1297.012 (rsc_running_container, CNFSM_CONTAINER_STATE) -- E_DSMP_CC_CONNECT_REQ -> (simple_voice_container, S_DSMP_VC_RUNNING)
1299.012 (rsc_running_container, CNFSM_CONTAINER_STATE) -- E_DSMP_CC_DISCONNECT -> (rsc_running_container, CNFSM_NO_STATE_CHANGE)

Session log information::
Regular Timer:
    Timer start operations:
             Timestamp    Duration(ms)        Caller
              2816.856            4000    0x61541F28
              2816.696            4000    0x61541F28
              2524.668            4000    0x61541F28
              2524.484            4000    0x61541F28
    Number of overwritten entries: 25

    Timer stop operations:
             Timestamp    Duration(ms)        Caller
              2816.868               0    0x615423B4
              2816.700               0    0x615423B4
              2524.676               0    0x615423B4
              2524.492               0    0x615423B4
    Number of overwritten entries: 26

Periodic Timer:
    Timer start operations:
    None
    Timer stop operations:
    None
Packet suppression is enabled

Stream information:: stream=7160
Type: TDM, Direction: INPUT
Fax/Modem Type: voice
Xmit Function: 0x00000000
Xmit function is Disabled
Call ID: 481, Conference ID: -1

Session information:: session=0x67756ECC dsp_intf=0x64227C00 dsp_name=1/2:1

connections=0 streams=4 (7160 7159 7158 7157 )
current state S_DSMP_VC_RUNNING current container simple_voice_container
State Transitions: timestamp (container, state) -- event -> (container, state)
1279.188 (simple_voice_container, CNFSM_CONTAINER_STATE) -- E_DSMP_DSP_DTMF_DIGIT_BEGIN -> (simple_voice_container, CNFSM_NO_STATE_CHANGE)
1279.320 (simple_voice_container, CNFSM_CONTAINER_STATE) -- E_DSMP_DSP_DTMF_DIGIT_END -> (simple_voice_container, CNFSM_NO_STATE_CHANGE)
1282.760 (simple_voice_container, CNFSM_CONTAINER_STATE) -- E_DSMP_DSP_DTMF_DIGIT_BEGIN -> (simple_voice_container, CNFSM_NO_STATE_CHANGE)
1282.892 (simple_voice_container, CNFSM_CONTAINER_STATE) -- E_DSMP_DSP_DTMF_DIGIT_END -> (simple_voice_container, CNFSM_NO_STATE_CHANGE)
1284.052 (simple_voice_container, CNFSM_CONTAINER_STATE) -- E_DSMP_DSP_DTMF_DIGIT_BEGIN -> (simple_voice_container, CNFSM_NO_STATE_CHANGE)
1284.184 (simple_voice_container, CNFSM_CONTAINER_STATE) -- E_DSMP_DSP_DTMF_DIGIT_END -> (simple_voice_container, CNFSM_NO_STATE_CHANGE)
1286.744 (simple_voice_container, CNFSM_CONTAINER_STATE) -- E_DSMP_DSP_DTMF_DIGIT_BEGIN -> (simple_voice_container, CNFSM_NO_STATE_CHANGE)
1286.876 (simple_voice_container, CNFSM_CONTAINER_STATE) -- E_DSMP_DSP_DTMF_DIGIT_END -> (simple_voice_container, CNFSM_NO_STATE_CHANGE)
1287.088 (simple_voice_container, CNFSM_CONTAINER_STATE) -- E_DSMP_DSP_DTMF_DIGIT_BEGIN -> (simple_voice_container, CNFSM_NO_STATE_CHANGE)
1287.220 (simple_voice_container, CNFSM_CONTAINER_STATE) -- E_DSMP_DSP_DTMF_DIGIT_END -> (simple_voice_container, CNFSM_NO_STATE_CHANGE)
1288.020 (simple_voice_container, CNFSM_CONTAINER_STATE) -- E_DSMP_DSP_DTMF_DIGIT_BEGIN -> (simple_voice_container, CNFSM_NO_STATE_CHANGE)
1288.152 (simple_voice_container, CNFSM_CONTAINER_STATE) -- E_DSMP_DSP_DTMF_DIGIT_END -> (simple_voice_container, CNFSM_NO_STATE_CHANGE)
1288.356 (rsc_running_container, CNFSM_CONTAINER_STATE) -- E_DSMP_CC_MODIFY_REQ -> (rsc_running_container, S_DSMP_MODIFY_CAPS_SAVED)
1288.356 (rsc_running_container, S_DSMP_MODIFY_CAPS_SAVED) -- CNFSM_LAMBDA_EVENT -> (rsc_running_container, CNFSM_CONTAINER_STATE)
1288.356 (rsc_running_container, CNFSM_CONTAINER_STATE) -- E_DSMP_CC_CONNECT_REQ -> (simple_voice_container, S_DSMP_VC_RUNNING)
1297.012 (rsc_running_container, CNFSM_CONTAINER_STATE) -- E_DSMP_CC_DISCONNECT -> (rsc_running_container, CNFSM_NO_STATE_CHANGE)
1297.012 (rsc_running_container, CNFSM_CONTAINER_STATE) -- E_DSMP_CC_MODIFY_REQ -> (rsc_running_container, S_DSMP_MODIFY_CAPS_SAVED)
1297.012 (rsc_running_container, S_DSMP_MODIFY_CAPS_SAVED) -- CNFSM_LAMBDA_EVENT -> (rsc_running_container, CNFSM_CONTAINER_STATE)
1297.012 (rsc_running_container, CNFSM_CONTAINER_STATE) -- E_DSMP_CC_CONNECT_REQ -> (simple_voice_container, S_DSMP_VC_RUNNING)
1299.012 (rsc_running_container, CNFSM_CONTAINER_STATE) -- E_DSMP_CC_DISCONNECT -> (rsc_running_container, CNFSM_NO_STATE_CHANGE)

Session log information::
Regular Timer:
    Timer start operations:
             Timestamp    Duration(ms)        Caller
              2816.856            4000    0x61541F28
              2816.696            4000    0x61541F28
              2524.668            4000    0x61541F28
              2524.484            4000    0x61541F28
    Number of overwritten entries: 25

    Timer stop operations:
             Timestamp    Duration(ms)        Caller
              2816.868               0    0x615423B4
              2816.700               0    0x615423B4
              2524.676               0    0x615423B4
              2524.492               0    0x615423B4
    Number of overwritten entries: 26

Periodic Timer:
    Timer start operations:
    None
    Timer stop operations:
    None
Packet suppression is enabled

Нормальный звонок:

voip_gate_test1#show voice dsmp stream leg 1137

Stream information:: stream=6027
Type: PACKET, Direction: OUTPUT
Fax/Modem Type: voice
Xmit Function: 0x6152A904
Xmit function is Enabled
Call ID: 1137, Conference ID: 257
DSP Encap: 0x1
Codec Mask: 0x4; Codec Bytes: 20
Fax Rate Mask: 0x2; Fax Bytes: 20; T38 Disabled
VAD Mask: 0x1

Session information:: session=0x677DFD54 dsp_intf=0x64229320 dsp_name=1/8:2

connections=2 streams=4 (6046 6045 6028 6027 )
current state S_DSMP_VC_RUNNING current container simple_voice_container
State Transitions: timestamp (container, state) -- event -> (container, state)
2883.672 (rsc_main_container, CNFSM_CONTAINER_STATE) -- E_DSMP_CC_MODIFY_REQ -> (rsc_main_container, CNFSM_NO_STATE_CHANGE)
2883.672 (rsc_main_container, CNFSM_CONTAINER_STATE) -- E_DSMP_CC_CONNECT_REQ -> (rsc_main_container, CNFSM_NO_STATE_CHANGE)
2883.672 (rsc_main_container, CNFSM_CONTAINER_STATE) -- E_DSMP_CC_MODIFY_REQ -> (rsc_main_container, CNFSM_NO_STATE_CHANGE)
2883.812 (rsc_main_container, S_DSMP_RSC_STARTING) -- E_DSMP_DSPRM_PEND_SUCCESS -> (rsc_main_container, S_DSMP_RSC_DYNAMIC_CONF)
2883.812 (rsc_main_container, S_DSMP_RSC_DYNAMIC_CONF) -- CNFSM_LAMBDA_EVENT -> (rsc_running_container, S_DSMP_MCAST_CHECK)
2883.812 (rsc_running_container, S_DSMP_MCAST_CHECK) -- CNFSM_LAMBDA_EVENT -> (rsc_running_container, S_DSMP_DTMF_FSK_MODE_CHECK)
2883.812 (rsc_running_container, S_DSMP_DTMF_FSK_MODE_CHECK) -- CNFSM_LAMBDA_EVENT -> (rsc_running_container, S_DSMP_NOT_DTMF_FSK)
2883.812 (rsc_running_container, S_DSMP_NOT_DTMF_FSK) -- CNFSM_LAMBDA_EVENT -> (simple_voice_container, S_DSMP_VC_RUNNING)
2883.812 (rsc_running_container, CNFSM_CONTAINER_STATE) -- E_DSMP_CC_MODIFY_REQ -> (rsc_running_container, S_DSMP_MODIFY_CAPS_SAVED)
2883.812 (rsc_running_container, S_DSMP_MODIFY_CAPS_SAVED) -- CNFSM_LAMBDA_EVENT -> (rsc_running_container, CNFSM_CONTAINER_STATE)
2883.812 (rsc_running_container, CNFSM_CONTAINER_STATE) -- E_DSMP_CC_MODIFY_REQ -> (rsc_running_container, S_DSMP_MODIFY_CAPS_SAVED)
2883.812 (rsc_running_container, S_DSMP_MODIFY_CAPS_SAVED) -- CNFSM_LAMBDA_EVENT -> (rsc_running_container, CNFSM_CONTAINER_STATE)
2883.812 (rsc_running_container, CNFSM_CONTAINER_STATE) -- E_DSMP_CC_CONNECT_REQ -> (rsc_running_container, CNFSM_NO_STATE_CHANGE)
2883.812 (rsc_running_container, CNFSM_CONTAINER_STATE) -- E_DSMP_CC_MODIFY_REQ -> (rsc_running_container, S_DSMP_MODIFY_CAPS_SAVED)
2883.812 (rsc_running_container, S_DSMP_MODIFY_CAPS_SAVED) -- CNFSM_LAMBDA_EVENT -> (rsc_running_container, CNFSM_CONTAINER_STATE)
2883.812 (rsc_running_container, CNFSM_CONTAINER_STATE) -- E_DSMP_CC_MODIFY_REQ -> (rsc_running_container, S_DSMP_MODIFY_CAPS_SAVED)
2883.812 (rsc_running_container, S_DSMP_MODIFY_CAPS_SAVED) -- CNFSM_LAMBDA_EVENT -> (rsc_running_container, CNFSM_CONTAINER_STATE)
2883.812 (rsc_running_container, CNFSM_CONTAINER_STATE) -- E_DSMP_CC_CONNECT_REQ -> (rsc_running_container, CNFSM_NO_STATE_CHANGE)
2883.812 (rsc_running_container, CNFSM_CONTAINER_STATE) -- E_DSMP_CC_MODIFY_REQ -> (rsc_running_container, S_DSMP_MODIFY_CAPS_SAVED)
2883.812 (rsc_running_container, S_DSMP_MODIFY_CAPS_SAVED) -- CNFSM_LAMBDA_EVENT -> (rsc_running_container, CNFSM_CONTAINER_STATE)

Session log information::
Regular Timer:
    Timer start operations:
             Timestamp    Duration(ms)        Caller
              2892.436            4000    0x61541F28
              2888.732            4000    0x61541F28
              2887.504            4000    0x61541F28
              2887.344            4000    0x61541F28
    Number of overwritten entries: 10

    Timer stop operations:
             Timestamp    Duration(ms)        Caller
              2892.444               0    0x615423B4
              2888.736               0    0x615423B4
              2887.516               0    0x615423B4
              2887.356               0    0x615423B4
    Number of overwritten entries: 11

Periodic Timer:
    Timer start operations:
    None
    Timer stop operations:
    None
Packet suppression is disabled

Stream information:: stream=6028
Type: PACKET, Direction: INPUT
Fax/Modem Type: voice
Xmit Function: 0x613C5638
Xmit function is Enabled
Call ID: 1137, Conference ID: 257
DSP Encap: 0x1
Codec Mask: 0x4; Codec Bytes: 20
Fax Rate Mask: 0x2; Fax Bytes: 20; T38 Disabled
VAD Mask: 0x1

Session information:: session=0x677DFD54 dsp_intf=0x64229320 dsp_name=1/8:2

connections=2 streams=4 (6046 6045 6028 6027 )
current state S_DSMP_VC_RUNNING current container simple_voice_container
State Transitions: timestamp (container, state) -- event -> (container, state)
2883.672 (rsc_main_container, CNFSM_CONTAINER_STATE) -- E_DSMP_CC_MODIFY_REQ -> (rsc_main_container, CNFSM_NO_STATE_CHANGE)
2883.672 (rsc_main_container, CNFSM_CONTAINER_STATE) -- E_DSMP_CC_CONNECT_REQ -> (rsc_main_container, CNFSM_NO_STATE_CHANGE)
2883.672 (rsc_main_container, CNFSM_CONTAINER_STATE) -- E_DSMP_CC_MODIFY_REQ -> (rsc_main_container, CNFSM_NO_STATE_CHANGE)
2883.812 (rsc_main_container, S_DSMP_RSC_STARTING) -- E_DSMP_DSPRM_PEND_SUCCESS -> (rsc_main_container, S_DSMP_RSC_DYNAMIC_CONF)
2883.812 (rsc_main_container, S_DSMP_RSC_DYNAMIC_CONF) -- CNFSM_LAMBDA_EVENT -> (rsc_running_container, S_DSMP_MCAST_CHECK)
2883.812 (rsc_running_container, S_DSMP_MCAST_CHECK) -- CNFSM_LAMBDA_EVENT -> (rsc_running_container, S_DSMP_DTMF_FSK_MODE_CHECK)
2883.812 (rsc_running_container, S_DSMP_DTMF_FSK_MODE_CHECK) -- CNFSM_LAMBDA_EVENT -> (rsc_running_container, S_DSMP_NOT_DTMF_FSK)
2883.812 (rsc_running_container, S_DSMP_NOT_DTMF_FSK) -- CNFSM_LAMBDA_EVENT -> (simple_voice_container, S_DSMP_VC_RUNNING)
2883.812 (rsc_running_container, CNFSM_CONTAINER_STATE) -- E_DSMP_CC_MODIFY_REQ -> (rsc_running_container, S_DSMP_MODIFY_CAPS_SAVED)
2883.812 (rsc_running_container, S_DSMP_MODIFY_CAPS_SAVED) -- CNFSM_LAMBDA_EVENT -> (rsc_running_container, CNFSM_CONTAINER_STATE)
2883.812 (rsc_running_container, CNFSM_CONTAINER_STATE) -- E_DSMP_CC_MODIFY_REQ -> (rsc_running_container, S_DSMP_MODIFY_CAPS_SAVED)
2883.812 (rsc_running_container, S_DSMP_MODIFY_CAPS_SAVED) -- CNFSM_LAMBDA_EVENT -> (rsc_running_container, CNFSM_CONTAINER_STATE)
2883.812 (rsc_running_container, CNFSM_CONTAINER_STATE) -- E_DSMP_CC_CONNECT_REQ -> (rsc_running_container, CNFSM_NO_STATE_CHANGE)
2883.812 (rsc_running_container, CNFSM_CONTAINER_STATE) -- E_DSMP_CC_MODIFY_REQ -> (rsc_running_container, S_DSMP_MODIFY_CAPS_SAVED)
2883.812 (rsc_running_container, S_DSMP_MODIFY_CAPS_SAVED) -- CNFSM_LAMBDA_EVENT -> (rsc_running_container, CNFSM_CONTAINER_STATE)
2883.812 (rsc_running_container, CNFSM_CONTAINER_STATE) -- E_DSMP_CC_MODIFY_REQ -> (rsc_running_container, S_DSMP_MODIFY_CAPS_SAVED)
2883.812 (rsc_running_container, S_DSMP_MODIFY_CAPS_SAVED) -- CNFSM_LAMBDA_EVENT -> (rsc_running_container, CNFSM_CONTAINER_STATE)
2883.812 (rsc_running_container, CNFSM_CONTAINER_STATE) -- E_DSMP_CC_CONNECT_REQ -> (rsc_running_container, CNFSM_NO_STATE_CHANGE)
2883.812 (rsc_running_container, CNFSM_CONTAINER_STATE) -- E_DSMP_CC_MODIFY_REQ -> (rsc_running_container, S_DSMP_MODIFY_CAPS_SAVED)
2883.812 (rsc_running_container, S_DSMP_MODIFY_CAPS_SAVED) -- CNFSM_LAMBDA_EVENT -> (rsc_running_container, CNFSM_CONTAINER_STATE)

Session log information::
Regular Timer:
    Timer start operations:
             Timestamp    Duration(ms)        Caller
              2892.436            4000    0x61541F28
              2888.732            4000    0x61541F28
              2887.504            4000    0x61541F28
              2887.344            4000    0x61541F28
    Number of overwritten entries: 10

    Timer stop operations:
             Timestamp    Duration(ms)        Caller
              2892.444               0    0x615423B4
              2888.736               0    0x615423B4
              2887.516               0    0x615423B4
              2887.356               0    0x615423B4
    Number of overwritten entries: 11

Periodic Timer:
    Timer start operations:
    None
    Timer stop operations:
    None
Packet suppression is disabled