Buyers considering a migration to VoIP often hit a wall at the very first turn in the decision tree: Hosted or on-premises? Now, buyers have a third alternative – blended architecture systems – that combine the best elements of both, while eliminating the downsides of each.

Purely hosted VoIP solutions don’t require much hardware or installation, so they are often presented as a low-cost, low-effort solution for smaller companies. In many cases, users can simply plug their new phones into a network jack and begin making calls. This plug-and-go aspect of hosted systems appeals to small and mid-size companies with little or no internal IT staff.

But as many users have found, purely hosted IP products have some substantial downsides. These issues often aren’t apparent until the system has been in use for a while, since many of the problems are intermittent in nature. Some of the problems users may encounter are:

• No quality of service: Data and voice packets must slug it out for priority. With no PBX (News - Alert) to prioritize data traffic, voice quality can suffer. A session border controller can be deployed to solve this problem, but SBCs increase complexity and cost.
• The session initiation protocol used by VoIP telephones does not work well behind firewalls that use network address translation. SIP-NAT problems often manifest themselves as dropped calls and/or one-way audio.
• Hosted VoIP solutions typically offer very limited monitoring, with finger pointing the likely result when problems arise.
• Most hosted VoIP is sold on a per-seat basis, and many VoIP providers charge an additional monthly fee for features such as voicemail and conference calling. Inexpensive for very small offices, true cost of ownership for moderate sized or larger organizations is usually higher than alternatives.

Many of the limitations of hosted VoIP can be overcome by using an on-premises IP PBX system. These systems typically manage QoS to provide increased call quality, but they add cost and complexity. Despite the added cost – in terms of initial purchase, ongoing maintenance, and power consumption – on-premises systems have their own set of shortcomings:

• Lack of redundancy: Many IP PBX systems offer multiple WAN interfaces to protect against an ISP failure, but they typically have little or no protection if the PBX itself should lose power or suffer a hardware failure. Some IP PBX vendors provide redundancy by using a second, parallel PBX, but this adds substantial cost and complexity.
• Little or no monitoring: Most IP PBX systems have limited monitoring features. Users and system administrators may not be aware of a system outage until they can no longer make or receive calls. Complex and expensive integration of multiple offices: Hosted VoIP solutions excel at uniting multiple business locations under a single dial plan. On-premises systems are less flexible because the call switching is performed in the PBX rather than in the cloud.

A new generation of VoIP products eliminates the problems of hosted and premises-based VoIP while delivering the best aspects of each. The most advanced of these new generation blended architecture solutions go even further, offering features and capabilities not found in either hosted or premises-based systems. Blended architecture systems combine the cloud-based telephony aspects of hosted VoIP with an on-premises PBX. Capabilities and features vary across vendors, but typical blended IP PBX systems handle call routing and data traffic management chores (including QoS) at the customer premises to provide call quality that is comparable to traditional systems.

While all blended systems use VoIP to connect and deliver telephony services, there are a variety of ways to deliver those services. For example, some systems store voicemail on the PBX itself, while others put the voicemail servers in the cloud. The same is true for other telephony features such as auto attendants and conference bridges.

Cloud-based telephony services – like their data-based counterparts – relieve local systems (and system administrators) of the burden of storing and backing up large amounts of voicemail and auto-attendant recordings. And since these services are in the cloud, they can continue to operate even if the IP PBX itself is down due to power or hardware failure or Internet outage.

Some blended architecture vendors provide 24/7monitoring and management services with their VoIP offerings. These services provide an additional level of comfort and are especially beneficial for smaller customers with limited IT resources or for bigger organizations that operate a large number of locations.

Randy Richardson (News - Alert) is chief product officer for Star2Star Communications LLC (www.star2star.com).