LRT to Route based on the FROM uri-user? and Regex in the user type?

Hi fellows,

I was trying to looking for a way to route extension just with 4 or 5 digits to the next hop SA. But I would like to make that based on the From uri-user

I think could be something like below example where user type is E164, but I would like to know if in the line of user type I can define any regular expresion?

for example   <user type="E164">!^\d{4,5}</user>

and then in the next hop I can define something like <next type="regex">!(^.*$)!sip:\1@ip_next_hop!</next>

Or If I can not define regular expresion in the user type then I could create something like