Architecture Overview
The PBX offers two ways to connect to external devices. First, you may register SIP user agents (UA), for example hard or soft phones, FAX or other SIP-compliant devices like conferences systems. Second, you may connect to the outside world via trunks.
The PBX supports several kinds of trunks. You may connect a regular SIP PSTN gateway to the IPPBX and terminate your calls to the PSTN through this gateway. The gateway does not need to support advanced features like transfer or dialog stage.
The second way to talk to the outside world is an Internet Service Provider that offers you SIP services. There are a number of service providers available that give you global coverage at excellent rates. If you want, you can use several trunks at the same time, for example one trunk for local or emergency calls, the other trunk for long
distance and international calls.
The IPPBX offers you the features that you know from your traditional PBX plus a feature set that can only come with the SIP-based technology.
Auto Attendant
The auto attendant handles the access to the extensions of the IPPBX. It supports IVRbased extension selection as well as the direct extension dialling. The auto attendant
checks if the extension is on Do Not Disturb (DND) and the call forwarding conditions (follow-me). You may have any number of auto attendants.
If the extension that the caller selected should be busy or unavailable, the caller can cancel the call and select another extension. The IPPBX supports multiple registrations with one extension number. When one of the handsets picks up, the other registered handsets are automatically canceled.
Users can dial star codes that control DND and call forwarding status of an extension.
Call Forward and Anonymous Calls
Users can program call forwarding on no answer, always and busy from the phone through the IVR system. If located in another location, users can place external calls from their extension code. This feature is helpful in public office areas (e.g. printer room) where the phone does not have outside call permissions.
Extensions may redirect anonymous calls to the busy destination. Extension may hide their extension number on external calls. These features are also controlled via the IVR interface.
Users can dial star codes that control DND and call forwarding status of an extension.
Multiple Appearance
SIP phones can register with the same extension several times. This is useful is you want to have phones in different locations, for example one in your office and another one at your home office. The IPPBX will ring all phones at the same time. When canceling a phone because of a pickup, it will send a message to the other phone that indicates that it did not miss a call.
Of course you may also have several extensions registered on one device. The IPPBX supports this feature also for the automatic configuration, where it well send the configuration information for all extensions.
Mailbox
If an extension is not available, the IPPBX may send the call to the mailbox. Extensions may subscribe to message waiting indications. Upon user request, the PBX will send
Emails when a voicemail has arrived (unified messaging).
The mailbox can be easily accessed with a star code or by dialing the extension number.
Most SIP devices support the automatic dialing of the mailbox indicated by the messages waiting indicator (MWI).
The mailbox supports the usual functions like urgent message marking, moving messages to other extensions, personal greeting and PIN code access from outside.
Conferencing
The PBX includes a simple conference mixer. You don't have to schedule conferences, just call into the conference room or blind transfer external participants into the conference number. You may set up any number of conference rooms on the IPPBX and you may protect them by a PIN code.
Hunt Groups
Hunt groups call extensions by a customizable call scheme. For each stage, you may specify which extension should be called and how long the IPPBX should stay on the stage. If all stages should fail, you can send the call to an automatic extension, such as an auto attendant or a park orbit. Each hunt group may have it's own ring tone (support of the extension required).
A Service Flag account can be used to define night service times. Users can call this number to turn night service on or off.
Push2Talk
For short group announcements, Push2Talk is a very nice and intuitive solution. If you call the Push2Talk extension number, all associated extensions will receive a one-way
audio call and playback the announcement. If your extension supports Push2Talk (PTT), you can easily tell your colleagues "hey folks, pizza is ready!" Even the remote workers that are connected to the IPPBX will hear the announcement.
Of course, you can set up a group with only two persons. This way, you can talk to you secretary and say "Moneypenny, can I have a cup of tea, please?"
Park and Pickup
When you put a call on hold, the other side will automatically hear music on hold, but you are still connected to that person.
Sometimes you want to park the call so that you or someone else can pick that call up from another place. For this purpose, the IPPBX provides park orbits. Park orbits can beassigned on group bases, so that the IPPBX knows where to park a call and from which orbit to pick up a call.
If you automatically direct calls into the park orbit, you end up in a queue. Call center agents can pick the calls up one after another and this way implement a waiting queue.
The IPPBX provides the information for SIP phones which is necessary to control LED keys. Phones that support the IETF draft dialog-state will be able to show you which lines are ringing and in use. You will be able to pick up calls in your hunt group and from your colleagues before your phone starts to ring by just pushing the key next to the LED.
Call Recording
You may record your calls by pushing a record button on your phone (works currently only with snom phones). The IPPBX will then record the conversation and send you the result in an email.
End-to-end Security
The PBX supports sips, srtp and sdes on all sip calls. This way you can keep the traffic between the IPPBX and the SIP device secure. Additionally, the professional version allows you to enforce end-to-end security. Here the IPPBX will allow calls only if the other side of the call also supports secure calls and if that is not the case it will tear down the call. For trunks, the administrator can specify which trunks are treated as secure and which trunks really need to communicate via secure protocols.
IVR Trees
You may set up your own IVR menus. Using the flexible extended regular expression scheme, you may set up the navigation between the different account types. Using the built-in simple recorder you can generate the voice prompts with a standard telephone. You may integrate an external application server using the SOAP XML standard (this feature is only available in the professional version). If you use this feature, you may include a database for making routing decisions. For example, you may first verify that the caller is an existing customer and start accounting for the call.
The IPPBX supports the most popular management methods. You can easily access the system with a web browser, either local or remote.
The web-based logging tool shows you the log messages, filtered by the log level. You don`t have to have access to the local file system for this task.
You may also see which calls are currently active and the call history. The calls data records (CDR) may be sent by http (professional edition) and are kept on a definable period in the system.
Trunks
Calls to the outside of the IPPBX are handled by trunks. Calls to trunks are handled by the B2BUA of the IPPBX, so that advanced features like transfer are not visible on the trunk side. This is an important feature for many ITSP providers that are not able to provide you this feature. You may set up any number of trunks. You can connect trunks to a local or remote PSTN gateway. A local PSTN gateway is very easy to set up and it will give you a good audio quality. If you want to take advantage of the attractive connection prices offered by today's Internet Telephony Service Providers (ITSP), you can register with such and ITSP and use the connection as trunk. That means all you internal extensions can place calls using this registration.
Dial Plans
You may set up dial plans that determine which trunk is being used for an external call. Dial plans may be assigned on an extension bases. This allows you to limit calls to certain destinations on a extension base. Dial plans are very flexible. The IPPBX uses extended regular expressions to match all kinds of input and use parts of it in the resulting destination pattern. The documentation shows frequently used patterns to make the installation process as simple as possible.
Security
The IPPBX authenticates SIP requests on a per-extension basis. Only the users that have the right password will be able to place outside calls or access their mailbox without entering their pin code. The authentication can be complemented by an IP-Address limitation. By providing this feature, you can specify the subnet from which a device is allowed to register or to make a call. Those devices which support the secure SIP standard sips, may use the TLS transport layer to talk to the IPPBX. This is an important feature for remote workers and officeswith a high security requirement. Needless to say that you can access the web server using https.
Call barge In and Listen in
A supervisor/ Attendant may barge into an ongoing call and speak or assist an agent. A supervisor may also listen in to a call in an non obtrusive manner
Interoperability
The IPPBX was designed to be strict on outgoing traffic, but tolerant in incoming traffic. This way, it is possible to support a wide range of devices along almost the complete feature set.. If you want to terminate your PSTN calls via any ITSP vendor.You can also terminate your calls locally with PSTN gateways. Choose your equipment from vendors like VegaStream.
Simple Phone Setup
Bringing devices into the system is very easy. Just set up some new user accounts and define the user name, the password and the email address. After creating the accounts, SIP devices may retrieve their configuration information directly from the IPPBX. You dont have to set up a tftp server and create the configuration files. The IPPBX comes with a built-in tftp server that generates the necessary configuration files on the fly. Please note that this feature is not available for all SIP endpoints. You may define that extension numbers are assigned on a first-come-first-serve basis, that extensions are assigned only if noone else is registered or explicitly specify the MAC address.
Remote Locations
The IPPBX supports multiple IP interfaces. That means you can run the IPPBX on a host that serves more than one IP address, for example ony public IP and one private IP. This way integrating remote offices becomes simple, if you use the TCP/TLS transport layer, you don't even need NAT traversal products to integrate those locations, even if they are behind NAT.
Multiple Domains
You may partition the user base into different domains, each of them corresponding to a different group of DNS names. For each or these domains you may specify ore or more domain administrators, so that these groups may set up extensions and other domainspecific features on their own.
SNMP
You can use standard SNMP tools to monitor the activity of the IPPBX. You can measure the busy hour call attempts and the busy hour calls, see how many registrations the IPPBX keeps and how many internal calls the IPPBX has open. Using the standard SNMP tools, you can for example send a message to your system integration for immediate action when something goes wrong.
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