Comment Re:well yeah (Score 2) 20
I don't work for T-Mobile but I do work in the Core Network design team of another mobile carrier in another country. Amongst those applications were undoubtedly a bunch of systems that are literally the mobile network itself, Virtual Network Functions (VNF) - things like HSS, MME, PGW etc. You can't just pick those up and flick them somewhere else on a whim. With the complexity of a modern mobile network 4 years would be on the short side for a program of work to move them. Especially since the move would realistically mean a shift to containerised versions instead of virtualised, which are an order of magnitude more complex to deploy.
Source: our company is in the throes of replacing large chunks of the core network with containerised functions (on RedHat OpenShift, which is the big telco vendors standard platform these days), currently in year three and have only completed HSS, with IMS ready to go live soon, OCS in the early stages, PCRF, messaging and the entire EPC yet to kick off in 2027-2028.