Hi Evren,

1. The UAC module uses a database table called `uacreg` as a list of credentials and registration destinations.

See:

https://github.com/kamailio/kamailio/blob/master/utils/kamctl/mysql/uac-crea...

2. You can trigger a registration manually with uac_reg_request_to() from route script:

http://kamailio.org/docs/modules/4.3.x/modules/uac.html#uac.f.uac_reg_reques..., mode)

However, this would be a rather hard thing to do in most cases since route script is generally only run when SIP messages are received (notwithstanding 'rtimer' and any special event_routes).

In general, the UAC module initiates these registrations when Kamailio first starts up, and then manages periodic registration renewal based on this setting:

http://kamailio.org/docs/modules/4.3.x/modules/uac.html#uac.p.reg-timer-inte...

Plus the expiration value in the `uacreg` table.

-- Alex