Chan_misdn alerting without connect

Hi all

I have an old asterisk pbx with a Dugium B410P board, CentOS5, asterisk 1.6.2.6, mISDN-1.1.9.2. The system behaved well for years, connected to various local telephony providers. Now my telco provider switched the old NT1 interfaces with a Cisco router with 4 PRI connections (they switched to voip, but absolutely they want to keep me with ISDN).
Almost all is working right, but in the new setup when I call certain numbers with an automatic responder, I simply get ringing tone. If I connect my pbx to an old plain NT1 and call the same numbers, I get the normal automatic responder messages. The telco technician connected a normal ISDN phone to the Cisco NT interfaces, and everything was right: the automatic responder was there.
He told me that the telco was sending the alerts with the audio inband data, but my pbx was not “hearing” them because they did not issue the connect. Is there a way to make asterisk work in this setup? I tried with “early_bconnect=yes” and “incoming_early_audio=yes” with no result.
I took a snip of the chan_misdn log, the last line “Starting Tones, we have inband Data” could be something related to my problem?

Mon May 30 133429 2016 P[ 1] CALL gTrunkPorts800018914
Mon May 30 133429 2016 P[ 1] – dad0800018914 techmISDNtmp0-u4 ctxfrom-pstn
Mon May 30 133429 2016 P[ 1] – adding2newbc ext 0800018914
Mon May 30 133429 2016 P[ 1] – adding2newbc callerid 59611111
Mon May 30 133429 2016 P[ 1] – pres -1 screen -1
Mon May 30 133429 2016 P[ 1] – pres 0
Mon May 30 133429 2016 P[ 1] – PRES Allowed (0)
Mon May 30 133429 2016 P[ 1] – SCREEN Unscreened (0)
Mon May 30 133429 2016 P[ 1] NO OPTS GIVEN
Mon May 30 133429 2016 P[ 1] I SENDSETUP oad59611111 dad800018914 pid4
Mon May 30 133429 2016 P[ 1] – channel0 modeTE cause16 ocause16 rad cad
Mon May 30 133429 2016 P[ 1] – info_dad onumplan0 dnumplan0 rnumplan0 cpnnumplan0
Mon May 30 133429 2016 P[ 1] – capsSpeech pi0 keypad sending_complete0
Mon May 30 133429 2016 P[ 1] – new_l3id 90003
Mon May 30 133429 2016 P[ 1] – SEND State Dialing pid4
Mon May 30 133429 2016 P[ 1] set_channel bc-channel255 channel1
Mon May 30 133429 2016 P[ 1] I IND NEW_CHANNEL oad59611111 dad800018914 pid4 stateCALLING
Mon May 30 133429 2016 P[ 1] – channel1 modeTE cause16 ocause16 rad cad
Mon May 30 133429 2016 P[ 1] – info_dad onumplan0 dnumplan0 rnumplan0 cpnnumplan0
Mon May 30 133429 2016 P[ 1] – capsSpeech pi0 keypad sending_complete0
Mon May 30 133429 2016 P[ 1] – updating channel name to [mISDN1-u5]
Mon May 30 133429 2016 P[ 1] – found chan (preselected) 1
Mon May 30 133429 2016 P[ 1] – TRANSPARENT Mode
Mon May 30 133429 2016 P[ 1] I IND SETUP_ACKNOWLEDGE oad59611111 dad800018914 pid4 stateCALLING
Mon May 30 133429 2016 P[ 1] – channel1 modeTE cause16 ocause16 rad cad
Mon May 30 133429 2016 P[ 1] – info_dad onumplan0 dnumplan0 rnumplan0 cpnnumplan0
Mon May 30 133429 2016 P[ 1] – capsSpeech pi0 keypad sending_complete0
Mon May 30 133429 2016 P[ 1] BCHAN bchan ACT Confirm pid4
Mon May 30 133434 2016 P[ 1] set_channel bc-channel1 channel-1
Mon May 30 133434 2016 P[ 1] I IND PROCEEDING oad59611111 dad800018914 pid4 stateCALLING_ACKNOWLEDGE
Mon May 30 133434 2016 P[ 1] – channel1 modeTE cause16 ocause16 rad cad
Mon May 30 133434 2016 P[ 1] – info_dad onumplan0 dnumplan0 rnumplan0 cpnnumplan0
Mon May 30 133434 2016 P[ 1] – capsSpeech pi0 keypad sending_complete0
Mon May 30 133438 2016 P[ 1] I IND ALERTING oad59611111 dad800018914 pid4 statePROCEEDING
Mon May 30 133438 2016 P[ 1] – channel1 modeTE cause16 ocause16 rad cad
Mon May 30 133438 2016 P[ 1] – info_dad onumplan0 dnumplan0 rnumplan0 cpnnumplan0
Mon May 30 133438 2016 P[ 1] – capsSpeech pi8 keypad sending_complete0
Mon May 30 133438 2016 P[ 1] Starting Tones, we have inband Data

Thanks for any help.
Luigi