asterisk users - Jul 2009 - Read/Write Codec formats

Hello!

I set my devices to only use g77a, but I am getting this when I run
show channel"

  NativeFormats: 0x8 (alaw)
  WriteFormat: 0x8 (alaw)
  ReadFormat: 0x4 (ulaw)

Why is ulaw (g711u) showing up for the Read Format?

Thanks,
Elliot