Handling of caller id code for private call

My grandstream device syslog returns this when receiving a “private” call:
2010-10-05 14:20:36 User.Debug 10.0.10.51 GS_LOG: [00:0B:82:22:F5:54][000][9660000311A][1.3.1.6] FXO_CID: Port: 0 Start cid analysis.
2010-10-05 14:20:36 User.Debug 10.0.10.51 GS_LOG: [00:0B:82:22:F5:54][000][9660000311A][1.3.1.6] FXO_CID: Port: 0----------- CID Reporting (FSK)-----------
2010-10-05 14:20:36 User.Debug 10.0.10.51 GS_LOG: [00:0B:82:22:F5:54][000][9660000311A][1.3.1.6] FXO_CID: Port: 0 Number : P (single message)
2010-10-05 14:20:36 User.Debug 10.0.10.51 GS_LOG: [00:0B:82:22:F5:54][000][9660000311A][1.3.1.6] FXO_CID: Port: 0 ---------- CID Reporting (end) ----------
2010-10-05 14:20:36 User.Debug 10.0.10.51 GS_LOG: [00:0B:82:22:F5:54][000][9660000311A][1.3.1.6] FXO_CID: Port: 0 Capture completed. Starts @ 0x80C5DC00 len=0000BB80
2010-10-05 14:20:36 User.Debug 10.0.10.51 GS_LOG: [00:0B:82:22:F5:54][000][9660000311A][1.3.1.6] FXO_CID: Port: 0 Finish cid analysis.

The “P” is not translated to “private” by the asterisk pbx. Call logs reflect this. I cannot create an inbound route for this condition. Where is this code interpreted by asterisk as private before parsing the extensions.conf?