There are network-based, software/desktop-based and hardware-based unified communications solutions. Is there a way to use a mixture of these approaches? If so, how?
Do you need advice?
This question speaks to both the complexity and amorphous nature of unified communications (UC). A much longer response is needed to do this justice, but here's a top-line commentary.
In today's market, most UC solutions have elements of all three -- cloud, software and hardware. To clarify the terminology in this question, when you say "network-based UC solutions," I take that to mean "cloud-based" or "hosted UC." The applications are indeed network-based, but hosted on someone else's network, typically that of a cloud provider. Whatever flavor of UC you deploy, it will certainly run over your network in order to make it available to your end users.
The second element is software-based, but these types of applications don't run exclusively on the desktop. This is really apples and oranges. Software describes the deployment model for UC, whereas the desktop is just one type of endpoint connected to your LAN, over which UC runs. Other UC-enabled endpoints would be desk phones, video conferencing monitors, smartphones and tablets. Increasingly, UC solutions are becoming software-based, mainly due to the lower cost along with the evolution of IP technologies. What was exclusively done on hardware just a few years ago can now routinely be done in software.
Most UC solutions involve a mix of hardware and software, where the former will typically be desk phones, conferencing phones/monitors, media gateways, session border controllers and possibly servers. The underlying applications will be software-based and optimized to run over the network. Conventional UC solutions will have this mix purely based on-premises, which means the applications will reside on-site. More recent offerings will be either partially or wholly cloud-based, meaning that the applications can reside either on-site or be hosted off-site. Businesses can go entirely this route or choose a hybrid approach, where some applications are hosted and others remain in-house.
For more information: Check out SearchUnifiedCommunications.com's on-premises vs. hosted cloud UC comparison chart.