Where does BSS end and OSS begin?

Over the years, I’ve been asked the question many times, “what’s the difference between OSS (Operational Support Systems) and BSS (Business Support Systems)?” I’ve also been asked, albeit slightly less regularly, how OSS and BSS map to TM Forum standards like the TAM (the Application Map) and eTOM (enhanced Telecommunications Operations Map).

To my knowledge, TM Forum has never attempted to map OSS vs BSS. It sets off too many religious wars.

At a high level, I believe the following statements would be agreed by most, regardless of their OSS/BSS religion:

• OSS are designed to be used by operations (ie back-office or internal staff). These tend to be used for internal (ie by carrier staff) functions like capacity planning, design, fault-fix, workforce management, inventory / asset lifecycle management, security, resource allocations and much more. These tend to be systems that are network-centric in nature.
• BSS tend to be much more customer-facing by nature. Even if these systems aren’t used directly by customers, they’re used by internal staff that are customer-facing. This includes functions like Customer Relationship Management (CRM), service order management (SOM), customer self-care portals, SLA management, product / offering design, sales management, contract management, billing, etc.

Just for fun, I thought I’d have a crack at trying to map OSS and BSS onto the TAM functionality map. Click on the image for a larger PDF version.

I’ve taken the perspective that customer or business-facing functionality is generally considered to be BSS. Alternatively, network / operations-facing functionality is generally considered to be OSS.
And these two tend to overlap at the service layer.

Or, you could just simply call them business operations systems (BOS) that cover the entire TAM estate.

What do you think? Does it trigger a religious war for you? Comments welcomed below.

FWIW. I come from an era when my “OSS” tools had a lot of functionality that could arguably be classified as BSS-centric (eg product management, customer relationship management, service order entry, etc). They also happened to deliver functionality that others might classify as NMS or EMS (Network Management System or Element Management System) in nature. In my mind, they’ve always just been software that supports operationalisation of a network, whether customer or network/resource-facing. It’s one of the reasons this site is called Passionate About OSS, not Passionate About OSS/BSS/NMS/EMS.