Are you sure it is an IVS?
If it is an IPS you can upgrade it to R8 3300 to allow the following feature that would help you. SMDR is not required.
The R8 Series 3300 IPS software enhancement allows 911 Notification to a Digital Dterm or IP Dterm when a station dials 911. On the Notification Dterm ringing and red flashing “EMG” key alerts that a station had dialed 911. The Notification Dterm goes off hook and presses the EMG key, the originating station number and destination trunk number is displayed on the LCD. By additionally pressing the “Override” key the Notification Dterm conferences into the 911 call and can assist in coordinating and directing
emergency services. When two or more Notification Dterm’s display the same caller information at the same time, the Notification Dterm that pressed the “Override” key first will conference into the 911 call. The other Dterm’s will receive ROT.
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If it is an IVS and don't want to upgarde to an IPS, you can try letter after v times 3 dot trisys dot com ( no websites allowed sorry) and check out the TAPIT software. Check out the NO SMDR Alarm portion, you can put up to 8 numbers in that if they are dialed it will screen pop the software. This will work with the NEC.