NEAX 2000 IVS2, DTERM keypads turn off after connect. 1

[owlguy]

All phone station numeric keypads (DTERM Series E) serviced by NEAX 2000 IVS2 suddenly quit functioning correctly.
Example 1 - dial voicemail, connects to voicemail (NEAXMAIL AD-40, functioning correctly for handsets serviced by different NEAX 2000 IVS2)which asks for numeric password, pressing keypad gives no response from numeric buttons. Access to voicemail from outside works flawlessly.
Example 2 - Dial outside to XYZWidget Company which answers with menu driven "Press 1 for help Press 2 if you know whats next" and pressing 1 or 2 does nothing. No tone heard in handset, or speaker if in speakerphone mode.
I cannot find the feature to toggle to allow the keypads to function again(perhaps I am searching on the wrong term).
The fault logs only show 1 entry the day this started "DTI line failure. Power Failure Kind : Frame loss/A synchronism of frame missed Data = (F1 FF FF FF FF FF FF FF)"
Does anyone have any ideas I could try to recover the functionality?

 

[belevedere]

The D-Term register/sender circuits are built in to the CPU. When you press a digit, a digital signal is sent to the CPU where a register/sender converts it to DTMF. You may have to try a system reset, or try to localize the problem to a specific PIM. Possibly a CP15 firmware processor card, or it could be the CPU itself. One other thing to try is a system shutdown and reseat the CPU. Unplug it then plug it back in. Old existing systems sometimes get tarnish on the CPU contacts to the back plane. A reseat creates a cleaner connection. It may sound silly, but it does sometimes clear up unusual problems.

 

[OzzieGeorge]

+1 for belvedere's solution. It used to be that a system reset was the first thing you tried with an NEC system (cured 90% of problems)!

 

[owlguy]

System Reset cleared the problem. Thank you everyone!