Management interface works too. It's very picky about end-of-line characters, which is a PITA when using Putty because it does not give you control over what it sends. You need to send "<command>;<cr><lf>".
Here's the response to the INV command:
INV=GPS STAR 4+,015880,1057,01,015881,0149,11022010,0010,8663-XS,0152;
This is:
INV=a,b,c,d,e,f,g,h,i;<cr><lf>
a: Name of the module (Max 12 char.) : GPS STAR 4+
b: Article number (Max. 6 characters) : 015880
c: Serial Number (Max: 6 characters) : 1057
d: Hardware version (Max. 2 characters): 01
e: Firmware article number (6 characters) : 015881
f: Firmware version (4 characters) : 0149
g: Date of test (format : DD/MM/YYYY) : 11/02/2010
h: Version of test system (Max. 4 characters) : 0010
i : Oscillator's type ( Max. 10 characters) : 8663-XS
j: FPGA version (4 characters) : 0152
Please post your units response to this command if you wire up the management interface. I'd like to see what range of firmware/hardware versions are out there.