This is the second in a seven-part blog series on migrating business communications services (e.g., Business VoIP and Unified Communications) to the cloud. The first blog, “Removing the Risk & Mystery from Cloud Migration,” focused on business risks for cloud migration and how communications service providers (CSPs) should address those risks.

We concluded with the need for businesses and CSPs to work together, and for CSPs to offer “productized” cloud migration solutions. CSPs should work with businesses as part of discovery and engagement to identify and address the specific business requirements and risks associated with cloud migration.

As service providers build out their migration offers, one of the most important offer elements relates to how aggressively to turn down legacy systems and turn up cloud communications services. This post will cover:

  • Strategic options around cut-over planning
  • How to approach planning
  • Tactics to drive the best outcomes for both businesses and CSPs


The Big Bang Approach

Some planners like to start with the proposal for a “big bang” cut-over. The big bang is a plan where legacy systems are all shut down at the same time followed by an immediate turn-up of new services. This type of cut-over is typically planned over a weekend and requires a highly orchestrated set of steps where services are managed in parallel for a period of time. For example, legacy systems are not actually shut down but are running in the background and made available for fallback in case of any issues with the new cloud service.

Many planners de-risk their cut-over plans by starting as a default with a big bang approach and working their way back to incremental deployments as they run into issues. The argument is that the big bang is the best starting point as the sooner the new service is implemented, the sooner the benefits of a new solution are received.

As we’ve already learned in “Removing the Risk & Mystery from Cloud Migration,” not every business values new features and capabilities relative to the risk of business disruption from cloud migration activities. In fact, we learned via an IDC study that 70% of buyers value risk reduction vs. immediate receipt of new capabilities and services.

Furthermore, big bang cut-overs neglect the sequence of how advanced services are typically adopted. In phase one of most migrations, both businesses and users are simply focused on being able to continue with execution of the business and completion of primary job activities, e.g., avoiding an outage or loss of mission-critical services. In phase two, users typically want to understand how the new cloud service offers the feature-functionality the users had with their previous premises-based system. Only after these two phases will a phase begin where users typically begin exploring new services and can take advantage of new productivity-enhancing solutions.

The risk is that aggressive “big bang” cut-overs never get beyond step one and cause disruptions to core business – impacting business operations and causing both user and customer issues. We believe that the “big bang” approach is, in fact, a sub-optimal starting point for migration planning. The larger and more complex the business requirements, the more that the CSP and business should start their migration planning using incremental strategies.

Recommendation: Incremental and structured migration plans offer a means to bring new cloud services online with less risk to business operations. For cloud communications services, we have identified two primary approaches for executing an incremental migration. These approaches can be applied independently or in combination.

Phased Services Migration

Delivered from the cloud, communications services can be structured and delivered in phased steps. For example, “line services” (e.g., hold, forward) that are associated with a user’s telephone number can be separated from “group” level services (e.g., hunt groups, IVRs) that are associated with virtual telephone numbers or collaboration services. Additionally, line services can be separated from “collaboration” services such as instant messaging and presence (IM&P) and meetings solutions such as Webex. In fact, a recent Frost & Sullivan survey suggests that businesses have already migrated (or consume) collaboration services with 61% and 59% of survey participants receiving their web and video conferencing from the cloud.

See below how collaboration services are already largely moved to the cloud. It is partially because some of these services were originally born in the cloud and also because these were migrated to the cloud as part of a phased project plan.

communications in the cloud instant messaging video conferencing telephony

Figure 1: TechTarget | Search IT Channel

Services can also be separated at the network level – allowing a migration from a TDM trunking service to a SIP trunk – delivering PSTN connectivity over an IP access link. In such a migration, existing PBX infrastructure can remain in place and the migration is effectively transparent to the end users.

Separating line, group, and collaboration services provides a wide range of options for CSPs and businesses to structure migration phases. An example of a fully phased services migration plan is as follows: Begin with the network services and in sequence,

  • replace TDM trunks with SIP trunks and SIP-based PSTN connectivity
  • replace group level services
  • replace and augment collaboration services
  • replace line equipment (PBX and phones) with cloud-based VoIP

The last step can be further broken into two phases – replacing existing line services and then implementing new user-level line services such as mobility-enablement (FMC and mobile clients).

Phased Site-by-Site Migration

Just as the name suggests, CSPs work with business IT to roll out new services, migrating WAN, LAN, and equipment related services one site (or set of sites) at a time. One of the key advantages of this approach is focus. It allows CSPs and IT planners the time needed to make sure that each site is completed and working before moving the team onto the next site or set of sites. 451 Research recently reported that one of the biggest gaps in planning cloud migrations is simply finding the qualified IT staff to support migration activity. A more focused migration strategy limits staffing demands compared to a broader, big-bang style rollout.

This approach also de-risks the migration and cut-over by limiting impact to a single site or set of sites. Lastly, this approach allows some learning-curve for any specific issues for a specific business. If there was an unanticipated equipment interop issue, this could be uncovered in an early migration site and be resolved before moving to follow-on sites.

Site-by-site migrations can put additional requirements on the service provider. For example, the CSP might be required to maintain dial plan continuity and services such as short dialing services across the phases of the migration – managing these in two or more systems. Although this represents additional work, this is often a better option than trying to do larger dial plan upgrades and porting across a large number of sites at once.

Site migrations can also be combined with the use of “hybrid” cloud deployment models. A common hybrid cloud model is the use of a “managed PBX” solution to facilitate cloud migration. We will explore the use of hybrid cloud at greater length in our third blog post. In advance of that, we can say that a site-by-site approach can be used to separate and focus on specific types of deployments. For example, smaller remote offices could be staged for a series of cut-overs to a multi-tenant / public cloud solution. Larger sites or a headquarters location could be staged as an entirely separate phase of the migration. In this approach, the division between migration to different types of cloud solutions allows both the CSP and IT managers to focus on specific and distinct requirements of each migration – once again de-risking the execution of each set of cut-overs.

In summary, there are many more ways to break-up migration elements to de-risk migration planning and cut-over execution. There are also additional considerations that can be factored into the planning process where incremental migrations will yield benefits for CSPs and IT managers – such as security. Understanding that security is something that is both multifaceted and can be looked at in multiple layers, it is possible to use an incremental migration plan to help structure security plans – possibly involving the coordination of third-party security experts in the planning process. In fact, Dimensional Research reports that over half of businesses decide to work with partners on their cloud migration strategy. This is more common among larger and enterprise deployments.

As CSPs offer templates, planning guides, and programs to manage incremental migrations and room to pull in third-party expertise, the greater the confidence of business IT leaders looking to move forward with a cloud communications deployment.



David Walters

Product Manager

Strategic Accounts and Initiatives