[Users] Comparable regex function in openser

Hello all, I am attempting to add a line to the SDP of a reply using subst. In perl I can do it like this. $test1 =~ s/(.+)\sRTP\/AVP\s18\s(.+)/$1 RTP\/AVP 18 $2\na=fmtp:18 annexb=no\n/g; This ensures I have the whole "m=audio 28104 RTP/AVP 18 101 19" string in the replacement I started with this: subst('/(.*) RTP\/AVP 18 (.*)/\1 RTP\/AVP 18 \2\r\na=fmtp:18 annexb=no\r\n/g'); As most of you probably can see this does not work. Does anyone know if this is possible? Thanks. This e-mail and any files transmitted with it are the property of AT&T Connecticut, are confidential, and are intended solely for the use of the individuals or entities to whom it is addressed. If you are not a named recipient, or otherwise have reason to believe that you have received this message in error, please notify the sender at phone 203-420-7225, and delete this message immediately from your computer. Any other use, retention, dissemination, forwarding, printing, or copying of this e-mail is strictly prohibited.