How will SDN be integrated with, OSS and BSS systems?
Presently, this is a big black hole with nothing much in it, but given the legacy that exists in every major telco, it's the biggest unanswered question in the SDN story.

How will the new environment be orchestrated?
There's a general recognition that an orchestration layer of some kind is required, but will this be accomplished by operators themselves, by vendor proprietary schemes, on the back of open source schemes such as OpenStack or through a new set of standards?

What's the relationship between NFV and SDN?
Some operators believe that NFV can bring benefits without using SDN (or at least Openflow) – others believe that they are joined at the hip. In 2013, we will see the first fruits of NFV, and with it the beginnings of an answer to this question.

What's the relationship between SDN, NFV and the various telco cloud programs?
Again, some telcos are trying to ensure that the three developments are coordinated, but though there clearly is a relationship, there's no defined roadmap for how it's constructed.

How far will the ONF be the prime location for SDN development?
Other initiatives already underway include the IETF's ForCES work, but such is the significance of SDN that we can expect other major industry organizations to get involved too.

Will operators really take the plunge and replace proprietary hardware with generic Ethernet switches and generic industry-standard servers?
Some already say yes, but when push comes to shove, will the famously conservative network engineering teams agree?

Equally, how will major suppliers respond?
Despite bold statements from some telcos, few will likely bet the network on start-up vendors, and will likely be dependent on their major suppliers for some time yet. But will those suppliers respond boldly to the new requirements or drag their feet?

How hybrid is hybrid, and for how long?
The ONF is working on a standard hybrid switch solution, but it's not yet clear what it will look like and whether big established vendors (some of whom already are touting their own hybrid solutions) will play along.

Where will telcos start with NFV and SDN?
Few, if any, expect a big bang – instead they will likely replace or augment existing networks and functions piece by piece. In its white paper, the NFV group sets out a long list of functions that might lend themselves to virtualization. But where will telcos start, and will they all start in the same place?

Can telcos resolve the many rivalries and tensions among their departments and divisions in a way that enables them to fully realize the benefits?
This brings us full circle, since the OSS question is right at the heart of this dilemma. Can the gap between IT and networks be bridged in an environment where some functions and divisions may disappear altogether?