Today’s business phone systems are a complex component of your IT stack. 
Along with physical phones, you may need gateways or SIP trunks, adaptors, and servers, but in some cases, this isn’t enough to make a phone system functional.
Here at The KR Group, Cisco Unified Border Element (CUBE) is another piece of technology we’ve started helping our infrastructure services customers incorporate into their IT stack.
This additional piece of technology bridges the gap for those IP phone systems that need more than a gateway or SIP trunk.
What is CUBE?
CUBE is Cisco’s solution for a session border controller for enterprise IP to IP traffic.
Session border controllers were originally created to allow media sessions to be established between user agents placed behind network address translations (NATs). They also improve SIP interoperability, connectivity, and security.
In less technical terms, session border controllers help your collaboration system work effectively and safely.
Just like you have measures in place to protect and regulate data, such as text files and emails, you need to take the same precautions with your voice network.
CUBE might sound complicated – and it is to an extent – but there are four fairly straightforward ways it can help your collaboration system:
- Direct routing
- IP out of both sides
- Security
- IP address translation
With these capabilities, CUBE can become a powerful tool in your collaboration system.
CUBE enables direct routing
One of the more recent features of CUBE is working with Microsoft to enable direct routing with CUBE for Microsoft Teams customers.
Microsoft Teams comes with a suite of PBX features, but it does not include dial tone.
While U.S.-based customers – and select countries around the world – can rely on a separate Microsoft Calling Plan to enable this feature, it isn’t available in every country. Most notably, it isn’t available in Mexico or India.
In terms of functionality, if you’re a U.S. business with locations in other countries that aren’t serviced by Microsoft Calling Plan, those phones won’t be able to call out of the office unless you create a SIP trunk.
With CUBE, you can create a SIP trunk to the Microsoft cloud, where your PBX features are hosted and enable outbound calls.
This means if you’re using Microsoft Teams for cloud-hosted collaboration, you can use CUBE to create a SIP trunk to the Microsoft cloud.
You can use these integrations to link Cisco Webex Calling users with Cisco BE6K or BE7K users, as well as the PSTN.
Using CUBE for dual IP connections
Enabling direct routing is a specific use case for CUBE. A more common one is if your telephone company provides you with IP dial tone.
To explain why you need CUBE in this situation, first, we need to back up and talk about how dial tone traditionally has reached your phone system.
Historically, the phone company side has been Plain Old Telephone Service (POTS) lines. This is analog voice transmission implemented over copper wires with one active caller per pair.
Its counterpart, ISDN PRI (integrated services digital network primary rate interface), entered the digital world with a T-1 circuit capable of carrying 23 active calls at once.
With either of these scenarios, you need a voice gateway to convert the audio from analog or digital signaling to IP traffic.
However, with advances in technology, now phone companies may offer an IP-based dial tone instead of analog or digital. This switch means you have IP-to-IP traffic and requires you to create a border to provide security for network traffic, which uses Session Initiation Protocol (SIP).
The border functions similarly to a voice gateway, except for the replacement of physical voice trunks with an IP connection.
CUBE routes IP calls from one VoIP dial peer to another by connecting the inbound dial peer to the outbound one.
CUBE provides security
Not only does CUBE route dual IP connections, but it also provides security.
Fraud is always a concern when it comes to audio – even with analog. An attacker could call into your phone system, and if you don’t have the right measures configured on your voice gateway (CUBE included), it is possible for the attacker to source outbound calls from your phone system.
A common example of this is an attacker making international calls using your phone system and leaving you with the bill.
With CUBE, you can prevent this from happening. The native security measures ensure only authorized systems are making calls, so unauthorized traffic can’t hijack your systems.
This is done by restricting which IP addresses are configured to make and receive calls.
CUBE translates IP addresses
Speaking of IP addresses, another common use for CUBE is to translate private IP addresses into public ones to prevent two users with the same address from being on the same call and therefore unable to connect.
Every network is assigned an IP address. Private IP addresses are reserved for business use and are restricted to a specific range, so there is a chance you could have the same IP address as the person on the other end.
As a session border controller, CUBE translates your private IP addresses to public ones to avoid this problem. This is an important element of CUBE because if this isn’t configured, your IP call system won’t work.
Use cases for CUBE
Not every IP business phone system requires CUBE, but if you find yourself in any of the below scenarios CUBE can be a helpful addition to your collaboration infrastructure:
- You need direct routing to an office that your cloud calling plan doesn’t cover.
- You need a border between your voice provider and voice network.
- You need security for your IP phone system.
- You need your private IP addresses translated to enable phone calls.
While these are some of the common use cases for CUBE, it just scratches the surface on what it can do.
For more information about how CUBE could work in your environment, check out Cisco’s datasheet.
