diff --git a/asterisk/AMI_Functions.ttcn b/asterisk/AMI_Functions.ttcn
index 53a7964..d5139f5 100644
--- a/asterisk/AMI_Functions.ttcn
+++ b/asterisk/AMI_Functions.ttcn
@@ -32,8 +32,21 @@
 type record AMI_Field {
 	charstring	key,
 	charstring	val
+} with {
+	encode "TEXT"
+	variant "SEPARATOR(': ', ':\s+')"
 };
-type set of AMI_Field AMI_Msg;
+
+type set of AMI_Field AMI_Msg with {
+	encode "TEXT"
+	variant "SEPARATOR('\r\n', '(\r\n)|[\n]')"
+	variant "END('\r\n', '(\r\n)|[\n]')"
+};
+
+external function enc_AMI_Msg(in AMI_Msg msg) return charstring
+	with { extension "prototype(convert) encode(TEXT)" }
+external function dec_AMI_Msg(in charstring stream) return AMI_Msg
+	with { extension "prototype(convert) decode(TEXT)" }
 
 template (value) AMI_Field
 ts_AMI_Field(template (value) charstring key,
@@ -102,49 +115,6 @@
  * Functions:
  */
 
-function f_AMI_Field_from_str(charstring str) return AMI_Field {
-	var AMI_Field field;
-	/* "each field is a key value pair delineated by a ':'.
-	 * A single space MUST follow the ':' and precede the value. "*/
-	var integer pos := f_strstr(str, ": ", 0);
-	if (pos < 0) {
-		Misc_Helpers.f_shutdown(__BFILE__, __LINE__, fail,
-					log2str("Failed parsing AMI_Field: ", str));
-	}
-	field.key := substr(str, 0, pos);
-	/* skip ": " */
-	pos := pos + 2;
-	field.val := substr(str, pos, lengthof(str) - pos);
-	return field;
-}
-
-function f_AMI_Msg_from_str(charstring str) return AMI_Msg {
-	var AMI_Msg msg := {};
-	var Misc_Helpers.ro_charstring lines := f_str_split(str, "\n");
-
-	for (var integer i := 0; i < lengthof(lines); i := i + 1) {
-		var charstring line := lines[i];
-		var AMI_Field field := f_AMI_Field_from_str(lines[i]);
-		msg := msg & { field };
-	}
-	return msg;
-}
-
-function f_AMI_Field_to_str(AMI_Field field) return charstring {
-	return field.key & ": " & field.val;
-}
-
-function f_AMI_Msg_to_str(AMI_Msg msg) return charstring {
-	var charstring str := "";
-
-	for (var integer i := 0; i < lengthof(msg); i := i + 1) {
-		str := str & f_AMI_Field_to_str(msg[i]) & "\r\n";
-	}
-
-	str := str & "\r\n";
-	return str;
-}
-
 private function f_ami_wait_for_prompt_str(TELNETasp_PT pt, charstring log_label := "(?)")
 return charstring {
 	var charstring rx, buf := "";
@@ -153,7 +123,7 @@
 
 	T.start(mp_ami_prompt_timeout);
 	alt {
-	[] pt.receive(pattern "\n") { };
+	[] pt.receive(pattern "\n") { buf := buf & "\n" };
 	[] pt.receive(charstring:?) -> value rx { buf := buf & rx; repeat };
 	[] pt.receive(integer:?) -> value fd {
 		if (fd == -1) {
@@ -174,7 +144,7 @@
 
 function f_ami_wait_for_prompt(TELNETasp_PT pt, charstring log_label := "(?)") return AMI_Msg {
 	var charstring buf := f_ami_wait_for_prompt_str(pt, log_label);
-	var AMI_Msg msg := f_AMI_Msg_from_str(buf);
+	var AMI_Msg msg := dec_AMI_Msg(buf);
 	return msg;
 }
 
@@ -185,9 +155,9 @@
 }
 
 function f_ami_transceive_ret(TELNETasp_PT pt, template (value) AMI_Msg tx_msg) return AMI_Msg {
-	var charstring tx_txt := f_AMI_Msg_to_str(valueof(tx_msg));
+	var charstring tx_txt := enc_AMI_Msg(valueof(tx_msg));
 	var charstring resp_txt := f_ami_transceive_ret_str(pt, tx_txt);
-	return f_AMI_Msg_from_str(resp_txt);
+	return dec_AMI_Msg(resp_txt);
 }
 
 function f_ami_transceive_match(TELNETasp_PT pt,