According to Dell’Oro Group, operators have spent 208% more on 5G SA than on 4G Core functions at the equivalent point in the technology lifecycle. With 5G SA investment continuing, operators need to make every network investment work harder.

The wider investment challenge is substantial. GSMA Intelligence estimates that Europe needs around €475 billion in mobile network investment by 2035, while only around €270 billion is currently expected to be accessible to operators, leaving a potential €205 billion investment gap.

The answer is not simply to spend less. Operators still need to evolve their networks. The challenge is to extract more value from infrastructure already in place while controlling the cost and complexity of transformation.

5G SA can ultimately simplify parts of network architecture, but operators do not move from one generation to another overnight. For many, 5G SA operates alongside 4G, IMS, Diameter, SS7, SIP, GTP and the interworking required between generations and external networks.

Every additional technology, interface and peer relationship can create another operational dependency, failure path or security boundary.

The consequences extend beyond CAPEX and OPEX. Signalling complexity can increase:

• Operational effort
• Failure exposure
• Security risks
• Project timelines of network transformations.

This makes the existing 4G signalling environment an important part of the 5G investment equation.

The 2026 Ookla/Omdia 5G SA and 5G Advanced Report found that globally, VoLTE had a median call setup time of 1.87 seconds, compared with 1.96 seconds for VoNR in its testing. The finding does not mean VoLTE is inherently superior; rather, it highlights how years of optimisation can allow mature technology to perform extremely well.

The lesson for operators is broader than voice. Before replacing mature infrastructure, they should ask where optimisation can reduce cost, improve security and extend commercial value.