[Serusers] How to send ALIAS as caller ID

Hello, I have working ser with all the db modules and lcr. I want to send useralias as caller id in place of user name. Say I have a ser account with the name testaccount, and an alias 15556667777 to the user testaccount. So if some one calls 15556667777 and the call will go to testaccount. Now if testaccount make an call then in the caller id I see testaccount. How can I send 15556667777 as caller ID when, testaccount make a PSTN call. I guess I can also use uri table and use the caller id from uri_user in place of username. But I dont know how can I do that. I tried this, modparam ("uri", uri_user_column", "uri_user") where the default is set for username. But That did not help. Thank you, -Jai