IBM won a major outsourcing contract in the early 2000s for Southern Europe (I know, I was there). I can assure you that they did not run the network because of a) sheer literal incompetence (they did not have the skills, in multiple regards) and b) the deal was solely for IT workloads and on an exclusive basis, and that did prevent many Vodafone staffers from actually fixing the messes IBM created.

(EDS won the northen countries, BTW, and I think things were marginally better with them, but either way, things soon reverted back to a more flexible arrangement because product development was severely hampered and most OpCos ended up rebuilding their IT systems)