Could you provide a review of the differences between Radio Alias and Caller Alias

Q. Could you provide a review of the differences between Radio Alias and Caller Alias, as well as the scenarios where each would be used? Additionally, does having a contact list set up impact how Caller Alias and Radio Alias function?

A. The Radio Alias is a 16-character alphanumeric string that is configured in the radio. This string is displayed when the radio powers on or the user goes into the My ID menu option (display model). It can also be useful to identify an unknown radio when it comes in for repair or programming. Other than this, the Radio Alias is not used anywhere else.

Radio Alias has limited impact on the contact list and vice versa. If there is no contact list entry for a transmitting radio, only the Radio ID will be shown.

Caller Alias (a.k.a. Inband Caller Alias or Talker Alias) is a feature that will embed a user-defined text string (up to unicode 31 characters) in all voice calls. Radios receiving the transmission from this radio will display the user-defined text string.

Caller Alias is described in ETSI TS 102 361-2 (v2.5.1) Section 5.4 so a radio from one manufacturer with caller alis setup, ought to be able to encode and decode caller aliases. A software application that supports this feature will also be able to decode this.

On a display-model radio, the user is able to go into the menu and change the caller alias though this functionality can be disabled (caller alias is fixed).

If a radio transmits and its Radio ID and Alias are present in the contact list of any receiving radio, the Radio Alias will be displayed. If the transmitting radio also has Caller Alias configured, a receiving radio will display the Radio Alias followed shortly by the Caller Alias. This will generally only happen once, since the receiving radio will cache received caller aliases.

If there is no contact list entry for a transmitting radio, the Radio ID will be shown for the first few seconds thereafter only the Caller Alias will be displayed.

Caller Alias would be useful on large systems where a specific radio user will communicate with more than 1000 radio users (i.e. more than what the contact list can accommodate). 

It would also be useful in applications where a radio is shared between users - each user can enter their name when starting their shift - this does however heavily rely on user honesty.

The limitation with Caller Alias is that it cannot be used to initiate calls. This means that if a user wants to make a private call to another user, they either need to know the Radio ID or the target radio needs to be in the calling radio's contact list. 

Also, Caller Alias cannot be used to identify a talkgroup, it will only identify a transmitting radio.