Limit multiple calls on a single phone

We are in the process of setting up Asterisk and will be using Iaxcomm as softphones. However, Iaxcomm will allow up to 100 multiple calls on a single phone.
How can we restrict this to one call from within Asterisk, therefore the 2nd caller will find the line busy and be directed to voicemail?
Platform used is Linux.

Use the ChanIsAvail() command to check to see if the IAX channel is in use before sending the call to the station.

Click here for information about the ChanIsAvail() command. … hanIsAvail

Thanks for your post.

We tried it, however it doesn’t work, subsequent calls still go to the active softphone.

Is there a command that once a call has been passed to a phone, that phone (and all its channels) is marked as unavailable and no other calls are routed to that phone until it is available again?

Just use the SetVar() command to set a “busy” variable any time an extension is called.

You can then check for the “busy” variable before you dial, and send calls to voicemail if the variable is set for a particular extension.

Ok Thanks, it works…

However, how can I use this command within the queue.conf or agents.conf, so that busy agents will not have their phone ringing?