Something

def edit
   @Codecs =  ["g729", "g723", "g726", "adpcm", "slin", "speex", "lpc10", "ilbc", "gsm", "ulaw", "alaw"]
   @sip_friend = SipFriend.find(params[:id])
   @allowed_Codecs = @sip_friend[:allow].split(';')
   @disallowed_Codecs = @sip_friend[:disallow].split(';')
   @avail_Codecs = @Codecs - @allowed_Codecs
   #@avail_Codecs -= @disallowed_Codecs
 end