[Serusers] ser 0.10.99 - call forwarding issue

hi! I am trying to set up the call forwarding feature and I have some question bout the idea how to realize this. My Idea was to do it with the usage of avp's. First thing I do is the check if there is a call_forward parameter set in the database in user_attrs table. I do this by invoking load_attrs("$fu", "$f.uid"); and then I do the check if ($tu.call_forward) On the "what's new site" in the avps and selects article I found another method which performs similar task: lookup_user("$tu","@ruri") What is the difference between those to methods?? Are they part of the SER core? previously in ser 0.9.x I have it done by, first loading the avp by avp_db_load() and then in case of call forwarding by making avp_pushto("$ruri","something") or rewriteuri() and then t_relay(). What is now a preferred way to realized similar functions. I mean can I utilize those methods like load_attrs or lookup_user() and then substitute the ruri without avp_pushto or rewriteuri?? best tomasz