Interfacing to TheLinkBox Program

This page has been moved to the wiki here.

Please use the wiki, as this information here is out of date.

This section is circa 2005, and it out of date. We encourage all people to use the latest install which can be found on

It is possible to interface an app_rpt installation with TheLinkBox Program (by Skip, WB6YMH), using the chan_tlb channel driver.

The connection(s) are accessed and referred to by a locally-assigned (private) node number, staring
with '1' (generally 1000-1999, as are any nodes not in the 'public' numbering space). Since the interface
is unique to the app_rpt installation, other app_rpt stations must first connect to the app_rpt node(s)
configured to connect with the desired TheLinkBox station(s).

Both TheLinkBox and app_rpt sides of the connection must choose a consecutive pair of UDP port numbers
on which to communicate (ports 44966/44967 typically) and also must both be on static IP addresses.

TheLinkBox supports the codecs ULAW, G726 and GSM. The app_rpt side of the connection dictates which
codec is to be used.

To enable TheLinkBox connectivity, there must be a file /etc/asterisk/tlb.conf specified as

call=WB6NIL-R           ; Call of the app_rpt station
port=44966              ; Start of UDP port range (this port, port + 1)
astnode=2008            ; app_rpt node associated with this instance (for incoming connections)
context=radio-secure    ; Asterisk context for incoming connections
codec=ULAW              ; Default CODEC to be used

1001 = W6ABC,,44966      ; This one is for W6ABC at ip default CODEC
1002 = W1XYZ,,1234,G726  ; This one is for W1XYZ at ip with G726 CODEC

You can, if you wish, have multiple instances under different sections (such as [tlb1], etc)
as long as they are on different UDP port pairs.

NOTE: The UDP port pair must start with an even port number. The even port is for the RTP (audio)
and the odd port is for the RTCP (control/supervisory).

On TheLinkBox side, you must specify the following in the main configuration file (generally

RTP_Port = 44966

And you must have an entry if your ACL file (generally tlb.acl) for each app_rpt node as follows:

allow   WB6NIL     -       -R

This particular example would allow station WB6NIL-R access from ip

NOTE: You must be running at least version 0.47 of TheLinkBox to use this feature.