diff --git a/ulaw.php b/ulaw.php
new file mode 100644
index 0000000..1c59ae1
--- /dev/null
+++ b/ulaw.php
@@ -0,0 +1,16 @@
+<?php
+define ("SIGN_BIT" ,0x80);
+define ("QUANT_MASK" ,0xf);
+define ("BIAS" ,0x84);
+define ("SEG_SHIFT" ,4);
+define ("SEG_MASK" ,0x70);
+
+// Converts ulaw to 16 bit signed lin
+function ulaw2lin($u_val)
+{
+        $u_val = ~$u_val;
+        $t = (($u_val & QUANT_MASK) << 3) + BIAS;
+        $t <<= ($u_val & SEG_MASK) >> SEG_SHIFT;
+        return /*pack("s",*/intval(($u_val & SIGN_BIT) ? (BIAS - $t) : ($t - BIAS))/*)*/;
+}
+?>