"All circuits are busy." when placing outgoing calls

Everytime I make an outgoing call I get the message “All circuits are busy.” After about a 15 minute wait I am able to place an outgoing call again. Could it be because i have more Phones than trunks? If so, How do would I fix this phone and trunk issue?

I am very new to this, I know versions and stuff need to be provided. Please tell me how to acquire those information if it is needed.

How Many trunks,phones.

The number of Trunks is the maximum number of outgoing calls you can make. 1 trunk = 1 outside call.

You don’t need a separate trunk for every phone, because you’re assuming that not everyone will be on the phone at one time. There’s a formula out there…, but it in truth, it really depends on how you use the system. As an average, you should figure 3 to 4 phones per trunk. But, in a smaller system you might need a higher number. Obviously, if you’re getting all trunks busy, you don’t have enough trunks and should add some more. How many you add, really depends on your situation.


Ip Phone online: 4
Ip Trunks online: 3

Is it normal for everyone to be on the phone at the same time?
Just depands on how you use the system. A smaller system usually has to have a greater trunk density. I’ve actually seen some systems that have more trunks than phones to allow for call queing and the leaving of voicemails…


This started happening when we got a new hire to make sales calls. However it is not common for all 4 phones or even 3 phones to be used at once.

You should identify the trunking you are using, if analog, there is a fair chance that you have mis-configured them especially if they “clear down” after a few minutes as you state.