Please note, this only applies in setups where billing is enabled on extension.
PBXware billing does not work in real-time, so in order to prevent misuse system must calculate the maximum length of the call before it starts.
Maximum call length is calculated by dividing available funds with route price per minute.
Now, this is correct only in cases where extension has one outbound channel available, otherwise, if the extension has multiple channels available, it could make an outbound call, put that call on hold and make a second call to another destination, spending more funds than it actually has.
To prevent this, PBXware also divides the maximum call length with the number of outbound channels, which in cases where extension has 4-5 channels can significantly shorten the maximum call length.
All this means, that if your extension has 10$ of funds available, and is calling a route that has a price of 1$ per minute, you would expect to be able to talk for 10 minutes before call is disconnected. However, if your extension has a limit of 5 outbound channels, these 10 minutes would also be divided by 5, so your maximum call length for this route will be 2 minutes.
Although, you will be left with 8$ on your funds and you will be able to start a new call once your call is disconnected after two minutes, your system will at one point think that your account is low on funds and send out an e-mail notification.