ubuntu*CLI> core show channel SIP/6004-00000003 
 -- General --
           Name: SIP/6004-00000003
           Type: SIP
       UniqueID: 1372708958.3
       LinkedID: 1372708958.3
      Caller ID: 6004
 Caller ID Name: 6004
Connected Line ID: (N/A)
Connected Line ID Name: (N/A)
    DNID Digits: 1001
       Language: en
          State: Up (6)
          Rings: 0
  NativeFormats: 0x200000000 (speex16)
    WriteFormat: 0x200000000 (speex16)
     ReadFormat: 0x200000000 (speex16)
 WriteTranscode: No 
  ReadTranscode: No 
1st File Descriptor: 16
      Frames in: 526
     Frames out: 22
 Time to Hangup: 0
   Elapsed Time: 0h0m10s
  Direct Bridge: <none>
Indirect Bridge: <none>
 --   PBX   --
        Context: internal
      Extension: 1001
       Priority: 2
     Call Group: 0
   Pickup Group: 0
    Application: Record
           Data: myspeexfile.wav,,,k
    Blocking in: ast_waitfor_nandfds
      Variables:
SIPCALLID=fef6e3d4eb3daa72990f0cba5cdf1ac2@0:0:0:0:0:0:0:0
SIPDOMAIN=127.0.0.1
SIPURI=sip:6004@127.0.0.1:42951


root@ubuntu:/var/lib/asterisk/sounds# file myspeexfile.wav 
myspeexfile.wav: RIFF (little-endian) data, WAVE audio, Microsoft PCM, 16 bit, mono 8000 Hz