Handset status across sip trunk

I am having some trouble with an asterisk install. I am not even certain that what I want to accomplish is possible.

I want to leverage asterisk queues to provide call center functionality in my Cisco Call Manager environment, rather than pay the outrageous agent license fees for cisco’s contact center product. I have a sip trunk built and it works well, I can pass calls to asterisk from my cisco phone and get calls back. The problem is that asterisk has no idea what the handset status is, so when a call comes into the queue i am using, it sends it to phones that are already in use. From quite a bit of searching on the internet, it seems that it is possible to send and receive this status, possibly by using subscriptions and hints. Unfortunately, I am not as knowledgable about this as I would like to be, so while I can recognize the terminology, I am not finding much documentation on the actual implementation of this.

Is what I am trying to do possible, and if so, how do I go about adding the necessary configuration?

Are you registering the phones directly with Asterisk or you’re just using Asterisk for queue management and have the phones register with CCM? You can use hints if you have the phones register with Asterisk.

All phones register to the call manager. Asterisk is configured merely with a sip trunk to call manager. Phones on the call manager can log into a queue via extension, which registers them as, for example, SIP/2990@CUCM. But as it is now, asterisk does not know if the extension is already in use, so if I call the queue, I immediately get a pop on my phone that is a new call coming from me on a second line. I don’t want this, I want it to go to the next phone in the queue if the first phone it tries is already off hook for any reason.

In this case Asterisk doesn’t know which phone is off hook, as the phones doesn’t register with it. As a workaround you could try disabling call waiting on the phones. I know this is not a solution to the problem, but with your current setup I can’t think of any other way to find out which phone is in use.