For buyers contracting authority
Pick 72315100 when the contract keeps an existing data network operational: fault resolution, a network help-desk, maintenance of routers and switches, and the technical support that surrounds live infrastructure. The accepted deliverable is uptime and responsiveness, not a new design.
The boundary that trips contracting authorities is the sibling 72315200, Data network management services. Management is the administration and operation of the network itself; support is the break-fix, maintenance and help layer on top. Where a single contract folds both together, which is common, set the primary CPV code by whichever dominates the statement of work, and reach for the parent 72315000 when the two are genuinely co-equal.
Two neighbours also matter. If the deal is mostly about telecoms transmission capacity rather than supporting the data layer, network services under 72720000 fit better. If it is general network installation and commissioning rather than ongoing support, that points elsewhere again. The cleanest test for 72315100: the work is recurring, it is about an already-built network, and support is the main purpose.