General information about Mitel Advanced Intelligent Network (AIN)

Mitel Advanced Intelligent Network(AIN) networks several MiVoice Office 400 communication servers into a single full-fledged communication system with a complete range of features. The individual nodes are independent of one another in terms of location and are controlled by a Master node. Networking is via the IP network.

With its consistent array of features throughout and a shared numbering plan the system as a whole presents itself as a single, homogeneous communication system, and the individual nodes are not perceived as such by the users.

The Master controls the other nodes (satellites). The Master is used to configure the satellites and update their software. This unique architecture greatly expands the application possibilities of MiVoice Office 400 systems, e.g.:

The modular expansion of system limits.
The integration of several sites and branch offices even beyond national and language borders.
The expansion of the DECT coverage range through roaming between nodes with overlapping radio area.

IP and SIP phones

Mitel SIP phones and IP system phones are fully integrated into AIN. They are controlled directly by the Master, independently of the location at which they are operated.

If a node is isolated from the Master by an interruption in the IP connection, it continues to operate in offline operating mode "Satellite in Offline Mode" with its own local configuration until contact with the Master is restored.

Resource-saving voice transmission

You can choose whether voice will be transmitted directly between two endpoints in the AIN (Direct switching) or via the Master (Indirect switching) (Setting ( Relay RTP data via communication server ). Direct switching (default setting) needs less resources, while indirect-switching is the potent method for systems with more demanding network configuration requirements. The signalling is always via the Master for both methods.

Bandwidth management

An ingenious bandwidth control prevents poor connection quality due to lack of bandwidth on the IP network.

Encrypting and deploying VPNs

Optional encryption of call and signalling data provides protection against any tapping and/or tampering of IP phone calls. The encryption methods used guarantee a high level of data protection, authenticity, integrity and protection against replay attacks throughout the network.

When you encrypt voice data in the AIN, it is encrypted within the LAN but not necessarily on WAN links. If a connection runs for example to a remote IP system phone via various internet providers, the voice data on the internet is not automatically encrypted. To encrypt the entire link you also need to set up a VPN (Virtual Private Network) for WAN links.

A VPN provides a secure passage through the internet from one point to the next (e.g. from the Master to the IP system phone or to the satellite) and is therefore particularly well suited for WAN links over the internet. The IP packets to be transmitted are encoded and re-packaged in IP packets (tunnelling). The most frequently used VPN protocols are IPsec and SSL.

A simple VPN links only two terminals or sites with each other. The internet provider's VPN services can be used to link several terminals or sites together via VPN. If using VPN in the AIN we recommend that whenever possible you work with a single internet provider who supports VPN routing and is able to cover all the locations. On the one hand this saves bandwidth resources and on the other it simplies the routing configuration.

TCP/IP Ports and Firewall

Firewalls used within the AIN must be configured for AIN operation. This includes opening the relevant ports and the VPN configuration.

With VPN connections the following ports must be opened on a firewall:

If a VPN connection terminates at the firewall itself, no port needs to be opened.
If a VPN connection terminates behind the firewall, e.g. directly at the terminal, port 3389 needs to be opened at the firewall (VPN pass through).
If a VPN connection terminates in front of the firewall, e.g. at a different firewall, the ports used by the AIN components need to be opened.
If all the WAN links in the AIN are VPN connections throughout and if they do not terminate at the firewalls themselves, port3389 only needs to be opened in the firewalls of the WAN links.
If the WAN links are only partly or not at all designed as VPN connections or if firewalls are also used within the LAN, the ports used by the AIN components must be opened. A list with the used ports is published by Support and continually updated. The list can be accessed on the internet under FAQ entry 1049 (registration required).

Restricted functions in the AIN

The AIN essentially provides the same features as a single system. Only a few functions are either not available or available only with restrictions:

Table 1. Functions not available or partially available in AIN
Parameter	Remarks
ISDN Data Services	ISDN Data Services and consequently Group 4 fax machines are not supported between the nodes of an AIN.
Call number and name display (CLIP/CNIP) of abbreviated dialing numbers	If two different abbreviated dialling numbers used in two nodes in different countries coincidentally have the same call number, the system does not know which name to display in the case of an incoming call. Remedy: Add the regional prefix to the call number.
Priority exchange allocation	The Priority Exchange Allocation system function External priority is also available when subsections of active call connections are routed via IP links. However, on the IP link itself no active call connections can be established for a prioritized call. Thus, if a prioritized call is to be established via an IP link, the link must have sufficiently free band width to be able to establish the connection without first having to disconnect an already active connection.
Key telephones and operator consoles	Line keys of key telephones and operator consoles are not taken into account when the bandwidth model checks the bandwidth requirement. The result is that a call on a line key is signalled even when insufficient bandwidth is available for the connection set up. When an attempt is made to answer the call, the connection is interrupted.

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