Affiliation is the act of a radio joining a talkgroup. On a trunked system a radio cannot transmit on, or receive calls for, a talkgroup until it has affiliated to it. The control channel tracks each radio's currently-affiliated talkgroup and uses that to decide who hears each call.
Only one talkgroup at a time. A radio holds exactly one affiliation; switching to a channel with a different talkgroupID deaffiliates from the previous one and affiliates to the new one.
| Step | Message | Notes |
|---|---|---|
| 1. Request | Radio sends AFFILIATE to the control channel with its Subscriber ID and the talkgroup ID. |
The radio must already be registered. |
| 2. Decision | Control channel checks the system's allow / deny rules. | Rules are evaluated per-system. |
| 3a. Allowed | Control channel records subscriber.affiliatedGroup = talkgroup and replies AFFILIATE_OK. |
The radio may now PTT and will receive calls on this talkgroup. |
| 3b. Denied | Control channel replies AFFILIATE_DENIED. |
The radio displays the denial and stays unaffiliated. |
| 4. Deaffiliation | Radio sends DEAFFILIATE, or selects a channel with a different talkgroup. |
The control channel clears affiliatedGroup and any active emergency alarm. |
Inside the radio, affiliation is tracked as one of three states:
AFFILIATE_OK or AFFILIATE_DENIED.Even an affiliated radio can receive CHANNEL_DENY on PTT. The most common reasons: