It is not possible to record DT700 VoIP phones from NEC if they are using the NECI firmware. This firmware implements a proprietary SIP protocol which only works with NEX PBXes, while Total Recall VR ‘understands’ standard (or open) SIP only.
The DT700 resource manual states that the phone can be upgraded from NECI firmware to standard SIP firmware. This can be done manually or automatically if the phone is connected to an NEC Spericall system version 7.1 or better.
Please contact NEC support for help on the upgrade – we cannot help you as we are not associated with NEC in any way.