дублируются цифры в DTMF

Добрый день, коллеги. После перехода на нового оператора возник плавающий глюк. При наборе добавочного номера asterisk воспринимает одну цифру как две и соответственно звонок уходит на совершенно другой номер телефона. Подскажите как побороть.

Лог звонка. Внутренний набирали 5194

[2018-03-22 09:04:05] VERBOSE[2970][C-00001e24] pbx.c: Executing [s@ivr:4] BackGround("SIP/RT-00001e24", "/var/lib/asterisk/sounds/ivr/IVR-1") in new stack
[2018-03-22 09:04:05] VERBOSE[2970][C-00001e24] file.c: <SIP/RT-00001e24> Playing '/var/lib/asterisk/sounds/ivr/IVR-1.gsm' (language 'ru')
[2018-03-22 09:04:09] DTMF[2970][C-00001e24] channel.c: DTMF begin '5' received on SIP/RT-00001e24
[2018-03-22 09:04:09] DTMF[2970][C-00001e24] channel.c: DTMF begin ignored '5' on SIP/RT-00001e24
[2018-03-22 09:04:09] DTMF[2970][C-00001e24] channel.c: DTMF end '5' received on SIP/RT-00001e24, duration 325 ms
[2018-03-22 09:04:09] DTMF[2970][C-00001e24] channel.c: DTMF end passthrough '5' on SIP/RT-00001e24
[2018-03-22 09:04:09] DTMF[2970][C-00001e24] channel.c: DTMF begin '1' received on SIP/RT-00001e24
[2018-03-22 09:04:09] DTMF[2970][C-00001e24] channel.c: DTMF begin ignored '1' on SIP/RT-00001e24
[2018-03-22 09:04:10] DTMF[2970][C-00001e24] channel.c: DTMF end '1' received on SIP/RT-00001e24, duration 495 ms
[2018-03-22 09:04:10] DTMF[2970][C-00001e24] channel.c: DTMF end passthrough '1' on SIP/RT-00001e24
[2018-03-22 09:04:10] DTMF[2970][C-00001e24] channel.c: DTMF end '1' received on SIP/RT-00001e24, duration 495 ms
[2018-03-22 09:04:10] DTMF[2970][C-00001e24] channel.c: DTMF end passthrough '1' on SIP/RT-00001e24
[2018-03-22 09:04:10] DTMF[2970][C-00001e24] channel.c: DTMF begin '9' received on SIP/RT-00001e24
[2018-03-22 09:04:10] DTMF[2970][C-00001e24] channel.c: DTMF begin ignored '9' on SIP/RT-00001e24
[2018-03-22 09:04:11] DTMF[2970][C-00001e24] channel.c: DTMF end '9' received on SIP/RT-00001e24, duration 370 ms
[2018-03-22 09:04:11] DTMF[2970][C-00001e24] channel.c: DTMF end passthrough '9' on SIP/RT-00001e24
[2018-03-22 09:04:11] VERBOSE[2970][C-00001e24] pbx.c: Executing [5119@ivr:1] Dial("SIP/RT-00001e24", "IAX2/DC/5119") in new stack
[2018-03-22 09:04:11] VERBOSE[2970][C-00001e24] app_dial.c: Called IAX2/DC/5119
[2018-03-22 09:04:11] VERBOSE[28053][C-00001e24] chan_iax2.c: Call accepted by 10.10.1.251:4569 (format gsm)
[2018-03-22 09:04:11] VERBOSE[28053][C-00001e24] chan_iax2.c: Format for call is (gsm)
[2018-03-22 09:04:11] VERBOSE[2970][C-00001e24] app_dial.c: IAX2/DC-25793 is ringing
[2018-03-22 09:04:11] VERBOSE[2970][C-00001e24] app_dial.c: IAX2/DC-25793 is ringing
[2018-03-22 09:04:11] DTMF[2970][C-00001e24] channel.c: DTMF begin '4' received on SIP/RT-00001e24
[2018-03-22 09:04:11] DTMF[2970][C-00001e24] channel.c: DTMF begin passthrough '4' on SIP/RT-00001e24
[2018-03-22 09:04:12] DTMF[2970][C-00001e24] channel.c: DTMF end '4' received on SIP/RT-00001e24, duration 530 ms
[2018-03-22 09:04:12] DTMF[2970][C-00001e24] channel.c: DTMF end accepted with begin '4' on SIP/RT-00001e24
[2018-03-22 09:04:12] DTMF[2970][C-00001e24] channel.c: DTMF end passthrough '4' on SIP/RT-00001e24
[2018-03-22 09:04:14] VERBOSE[2970][C-00001e24] chan_iax2.c: Hungup 'IAX2/DC-25793'
[2018-03-22 09:04:14] VERBOSE[2970][C-00001e24] pbx.c: Spawn extension (ivr, 5119, 1) exited non-zero on 'SIP/RT-00001e24'

В sip.conf прописано

dtmfmode=rfc2833