Detect if extensions its using?

I’m triying to detect if some extensions are in using, go to voicemail ex:

I call to => 430 (if this extension it’s using at this time go to voicemail of this user)

Help me, thank’s

If you are using sip you can use call-limit=1 so that the phone can only have one call at a time.

OK, but, how i can make to when someone call to 209 and if this extensions it’s busy, call to extensions 210.
HOw can i do this?

Have a look at chanisavail: … hanIsAvail