@miconda, Kamailio has its own RADIUS dictionary and attributes. But we need to send custom auth request. Here is example from Cisco VoIP:
User-Name = "74951011123" Calling-Station-Id = "74951011123" Called-Station-Id = "74951234567" Service-Type = 30 Acct-Session-Id = "93F51D6D 1FD111E0 99AD0014 F26ABCA0" Cisco-AVPair = "xpgk-remote-id=kamailio" Cisco-AVPair = "xpgk-src-number-in=74951011123" Cisco-AVPair = "xpgk-dst-number-in=74951234567" h323-conf-id = "93F51D6D 1FD111E0 99AD0014 F26ABCA0" h323-call-origin = "originate" h323-call-type = "VoIP" NAS-Port = 0 NAS-IP-Address = 192.168.1.1
And thought to do it with auth_extra string. But faced with a limitation MAX_EXTRA.To make it universal I propose to make a sufficiently large number. Then it will be possible to write a request and emulate the request from any equipment. Also be able add custom dictionaries from FreeRADIUS to Kamailio: radis_dictionary_add('custom_dict_file'). Then the request can be made using the fields of custom dictionaries.