Hello
When need to assign variable value with XML symbols requires escaping is suggested to use dialplan contractions like example
<action application="set"><![CDATA[sip_h_Call-Info=<urn:nena:uid:callid:72270801514820004831:lng.001.experient.co.us>;purpose=nena-CallId]]></action>

But more elegant will be
<action application="set" data="sip_h_Call-Info=&lt;urn:nena:uid:callid:72270801514820004831:lng.001.experient.co.us&gt;;purpose=nena-CallId"/>

I want add this functionality to FS. Could you give me reference to FS code where is used escaping/unescaping. 

Sergey