anchor.diff:  
     buildInputs = [
       readline openldap cyrus_sasl libupnp zlib libxml2 gtk2 libnotify speex ffmpeg libX11
  -    polarssl libsoup udev ortp mediastreamer sqlite belle-sip libosip libexosip
  +    libsoup udev ortp mediastreamer sqlite belle-sip libosip libexosip
     ];
   
     nativeBuildInputs = [ intltool pkgconfig makeWrapper ];
  
positive.code: { stdenv, fetchurl, intltool, pkgconfig, readline, openldap, cyrus_sasl, libupnp
  , zlib, libxml2, gtk2, libnotify, speex, ffmpeg, libX11, polarssl, libsoup, udev
  , ortp, mediastreamer, sqlite, belle-sip, libosip, libexosip
  , mediastreamer-openh264, makeWrapper
  }:
  
negative.code:   configureFlags = [
      "--enable-ldap"
      "--with-ffmpeg=${ffmpeg.dev}"
      "--enable-external-ortp"
      "--enable-external-mediastreamer"
    ];
  