--- a/doc/Calypso-TCH-downlink	Fri Dec 30 07:23:24 2022 +0000
+++ b/doc/Calypso-TCH-downlink	Fri Dec 30 07:46:58 2022 +0000
@@ -109,3 +109,11 @@
   gsmx and calling library functions directly, and thus there is no FR1
   counterpart to gsmefr-dlcap-dec - just use gsmfr-dlcap-gsmx followed by
   gsmfr-decode or gsmfr-decode-r.
+
+* In addition to TCH DL capture files, gsmfr-dlcap-parse also accepts the hex
+  output from fc-vm2hex, originating from TCS211 voice memo recordings,
+  including fc-vm2hex output in the case of VM recordings made in DTX mode.
+  However, if the objective is to play that VM recording and not just look at
+  parsed bits, the correct approach is to convert the VM file to gsmx with
+  fc-vm2gsmx, and then decode with gsmfr-decode.  Using fc-vm2hex followed by
+  gsmfr-dlcap-gsmx instead of fc-vm2gsmx won't work!