how to configure entry in LRT

Hello,

we have SBC in enterprise environement with various PBXs on the south. Therefore we need to do the routing using LRTs. It is a standard LRT with request URI as a key and should be looking like this:

<route>

<user type="E164">500025</user>

<next type="regex">!^\+(.*$)!sip:\1@xxx.xx.xx.xxx;egress=OXE!</next>

</route>

I have doubts about the line <next type="regex">!^\+(.*$)!sip:\1@xxx.xx.xx.xxx;egress=OXE!</next>

In some examples I found sip:\1@xxx.xx.xx.xxx;</next>, and in some sip:\0@xxx.xx.xx.xxx;</next>. Which one should I use \1 or \0, I don't need to change request uri.