How to setup correct DTMF recognition by Asterisk with ATC Panasonic?

Question

Asterisk

There are two offices, in one - PBX Panasinic NCP 1000, with SIP and system IP phones (KX-NT543), connected via E1 stream.
In another Asterisk, SIP directly from the ISP. When calling to the second office from SIP phones, the extension dialing signal is recognized correctly. If you dial from system phones, the DTMF signal is not recognized correctly (only a part of the dialed number can be received with the omission of random digits, i.e. 10, 11, 12 or 1 instead of 102). At the same time, such a problem is only when calling to Asterisk's IVR, calls to other companies go through correctly. As well as on Asterisk'e signals only from system phones are not perceived. Calls from mobile\landline numbers\SIP phones of the first office go through normally.
Asterisk settings were checked with the provider, dtmfmode=rfc2833, relaxdtmf=yes.
Help to deal with the situation, it is not even possible to properly localize the malfunction.

Answer 1

Try different dtmfmode values ​​for the PBX trunk, specifically inband . Will behavior change?

Answer 2

What is the signaling on the E1 stream? What iron on the side of the asterisk receives the stream?