Sizing up VoIP servers

3Com, Avaya, Siemens, and Zultys offer rich telephony features, excellent voice quality, and more or less scalability

One nice feature is a backup utility that supports a magneto-optical disk. If something bad happens to your PBX, at least you won't have to start again from scratch. In addition, you can network the HiPath 4000 to other Siemens units for redundancy. Likewise, the HiPath 4000 itself can carry redundant processors and power supplies for those mission-critical applications (aren't nearly all phone systems mission critical?). Networked HiPaths can be administered centrally.

In addition to hardware redundancy, Siemens also provides backup management options. Along with the Web management interface, the company includes not only a CLI, but also an X Windows client.

Finally, Siemens' own softphone is pricey, and although the company does not support the use of the X-Ten and 3Com softphones, both are much less expensive and they work just fine.

Zultys MX250

The good news about the Zultys MX250 is that it's completely standards-based. This is a pure SIP PBX. The bad news is ... well, there isn't any bad news. This PBX did exactly what the people at Zultys said it would do and did it very nicely indeed. Even better, because it is a standard SIP implementation, it worked perfectly with our Spirent Abacus test equipment and we were able to confirm that the product performs exactly as Zultys says it will. The voice quality, as we've learned to expect from today's IP phones and PBX hardware, was excellent.

The MX250 itself is a 2U box with dual IBM PowerPC processors running MontaVista Software's Hard Hat Linux. The company says that the MX250 was designed from the ground up as an IP PBX platform, rather than being a telephony platform with IP grafted on, or a computer with telephony grafted on. While it's not clear that this gives the MX250 any real operational advantages, what is clear is that this product is nicely integrated and feature rich.

While the MX250 is limited to 250 users, you can network 32 MX250s together over Ethernet to support as many as 8,000 users. Zultys includes a management application that runs on Windows, which is downloaded from the MX250. There's also a Web-based management interface.

Adding users requires only a simple form, but if you have a lot of users, you can upload a CSV file created using Excel or something similar. The company says that an LDAP interface will be available in the near future.

One of the benefits of a standards-based PBX is that it will support inexpensive, nonproprietary devices. While we used the ZIP 4X4 IP telephone from Zultys for the tests, you can use any phone that meets SIP standards. This includes SIP-based softphones and software such as Microsoft Windows Messenger (assuming Service Pack 2 doesn't change things).

Most of the telephony features you're likely to want are included with the MX250. Voice mail is standard (storage is handled by up to two SCSI hard drives) and you get automated attendants, multiple operator groups, fax termination and origination, multimedia switching, and flexible connections to the PSTN.

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Management is straightforward. You can configure phones and most other SIP devices from the PBX, and the whole shebang will work over a shared Ethernet network as long as it supports QoS. You even get a secure instant messenger and secure voice connections. The MX250 supports 128-bit AES (Advanced Encryption Standard) encryption internally (unlike the Avaya PBX, the Zultys allows you to control whether it's used), and you can encrypt external traffic across the PSTN or your private network if you're going to link another MX250. The product also includes its own internal firewall and it supports IPSec VPNs.

We were impressed by Zultys' interface for end-users. This tool is designed to let users manage their own phones and calling rules to the extent allowed by the IT manager. In addition to giving users more flexibility in how they make and receive calls, this offloads some of the work otherwise done by the IT department.

While you won't be able to run a medium-sized city or a massive enterprise with the MX250, you'll be able to support most organizations. The standards support and security features work together to make the Zultys MX250 a great option for small and midsize businesses.

All four of these platforms are good choices for businesses. You'll notice that we didn't find any losers here. What we did find is that, despite their common purpose, these are very different products. They're suited for enterprises of varying sizes and differing needs. It's likely that for any given company, only one, perhaps two, of the products reviewed here is even relevant. After all, if you have 150 people in your company, you're probably not shopping for the Avaya S8700. And if you have 20,000 people, the Zultys isn't going to meet your needs.

In addition, a great deal depends on how important some characteristics and features are to your organization. Is your company a stickler for standards support? Do you need extremely high availability? Is your enterprise in one location or spread across the globe? All of these will influence your choice of a telephone system.

Interestingly, price is not one of the differentiating factors. User for user, feature for feature, these products are in the same ballpark. Yes, there are some differences in pricing, but probably not enough to make the critical difference in such a capital expenditure. What matters more is that the PBX meets your needs and whether it will fit into your organization with an acceptable level of disruption. All of these products can do that, but whether they will depends on your staff, organization, and infrastructure, at least as much as on the product itself.


In this review, we originally erred in describing a few features of the Siemens HiPath 4000. The HiPath's operating system is UnixWare8. It supports a maximum of 100,000 stations per network, and it can encrypt voice communications. Siemens does not support the use of X-10 or 3Com softphones with the HiPath system. The review has been corrected.

InfoWorld Scorecard
Setup (10.0%)
Management (30.0%)
Value (10.0%)
Scalability (20.0%)
Features (30.0%)
Overall Score (100%)
3Com VCX V7000 IP Telephony Solution, v. 5.0 9.0 8.0 8.0 8.0 8.0 8.1
Avaya S8300 and S8700 Media Servers 8.0 9.0 8.0 9.0 9.0 8.8
Siemens HiPath 4000 Real-Time IP System, v. 2.0 8.0 9.0 8.0 9.0 9.0 8.8
Zultys MX250 Enterprise Media Exchange 9.0 8.0 8.0 8.0 9.0 8.4
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