Freeswitch 报SYNTHESIZER channel error

[sevenler]

2019-03-28 20:41:19.130070 [INFO] mrcp_sofiasip_client_agent.c:609 () Receive SIP Event [nua_i_state] Status 0 INVITE sent [unimrcpserver-mrcp2]
2019-03-28 20:41:19.130070 [NOTICE] mrcp_sofiasip_client_agent.c:547 (TTS-1) SIP Call State TTS-1 [calling]
2019-03-28 20:41:19.130070 [INFO] mrcp_sofiasip_client_agent.c:609 () Receive SIP Event [nua_r_invite] Status 503 Service Unavailable [unimrcpserver-mrcp2]
2019-03-28 20:41:19.130070 [INFO] mrcp_sofiasip_client_agent.c:609 () Receive SIP Event [nua_i_state] Status 503 Service Unavailable [unimrcpserver-mrcp2]
2019-03-28 20:41:19.130070 [NOTICE] mrcp_sofiasip_client_agent.c:547 (TTS-1) SIP Call State TTS-1 [terminated]
2019-03-28 20:41:19.130070 [INFO] mrcp_client_session.c:151 (TTS-1) Receive Answer TTS-1 [c:0 a:0 v:0] Status 503
2019-03-28 20:41:19.130070 [INFO] mrcp_client_session.c:455 (TTS-1) Raise App Response TTS-1 [2] FAILURE [2]
2019-03-28 20:41:19.130070 [ERR] mod_unimrcp.c:1913 (TTS-1) SYNTHESIZER channel error!
2019-03-28 20:41:19.130070 [INFO] mrcp_client_session.c:387 (TTS-1) Receive App Request TTS-1 [1]
2019-03-28 20:41:19.130070 [INFO] mrcp_client_session.c:833 (TTS-1) Terminate Session TTS-1
2019-03-28 20:41:19.130070 [INFO] mrcp_client_session.c:209 (TTS-1) Session Terminated TTS-1
2019-03-28 20:41:19.130070 [INFO] mrcp_client.c:710 (TTS-1) Remove MRCP Handle TTS-1
2019-03-28 20:41:19.130070 [INFO] mrcp_client_session.c:455 (TTS-1) Raise App Response TTS-1 [1] SUCCESS [0]
2019-03-28 20:41:19.130070 [NOTICE] mrcp_application.c:182 (TTS-1) Destroy MRCP Handle TTS-1
2019-03-28 20:41:19.130070 [ERR] switch_ivr_play_say.c:3008 Invalid TTS module!
2019-03-28 20:41:19.130070 [NOTICE] switch_cpp.cpp:723 Hangup sofia/internal/1000@10.211.55.16 [CS_EXECUTE] [NORMAL_CLEARING]
2019-03-28 20:41:19.130070 [NOTICE] switch_core_session.c:1683 Session 1 (sofia/internal/1000@10.211.55.16) Ended
2019-03-28 20:41:19.130070 [NOTICE] switch_core_session.c:1687 Close Channel sofia/internal/1000@10.211.55.16 [CS_DESTROY]

在文章中的讨论中也有人提到这个问题