From this guide, I know that FreeSwitch (FS) will load modules, each module would provides some commands and all these commands can be accessed from FS_CLI or ESL.
Here is my test:
1/ Show available commands from FS_CLI:
freeswitch@my-pc> show api
name,description,syntax,ikey
...,Shutdown,,mod_commands
acl,Compare an ip to an acl list,<ip> <list_name>,mod_commands
alias,Alias,[add|stickyadd] <alias> <command> | del [<alias>|*],mod_commands
banner,Return the system banner,,mod_commands
bg_system,Execute a system command in the background,<command>,mod_commands
bgapi,Execute an api command in a thread,<command>[ <arg>],mod_commands
.... other commands....
And I don't see api command from above list.
2/ Try to run api command from Inbound socket connection:
➜ ~ telnet localhost 8021
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
Content-Type: auth/request
auth ClueCon
Content-Type: command/reply
Reply-Text: +OK accepted
api msleep 2000
Content-Type: api/response
Content-Length: 3
+OK
3/ Try to run api command from FS_CLI:
freeswitch@my-pc> api msleep 2000
-ERR api msleep 2000 Command not found!
Pls, help me to explain why #2 worked but not #3 (afaik FS_CLI utilizes socket under the hood)
Try to remove api in the command it should work.
freeswitch@ip-172-31-33-109> msleep 2000
+OK
You need to add api when try to call a command outside of CLI in CLI no need to add api without it's work.