For a tech-adjacent example of an acquisition of an entrenched supplier, look at Tekelec, a telecom hardware and software vendor which Oracle purchased in 2013[1].
Tekelec had a number of products but Oracle really cared about one: the EAGLE family, which is a suite of hardware and software for handling network signaling and routing over SS7. For any customer, EAGLE sits at the core of their networks and it is why your calls actually get connected and billed correctly.
EAGLE had a customer base that included nearly all of the important global telecom carriers. From the press release:
> Tekelec’s technology enables service providers to deliver, control and monetize innovative and personalized communications services and is utilized by more than 300 service providers in over 100 countries.
Verizon[2][3] runs EAGLE STP in their core, as does AT&T[4] (f/k/a SBC). Old business win press releases from Tekelec mean Bell Canada and Rogers still likely do. Based on job postings, Vodafone and Virgin Mobile use EAGLE STP for exchanging SS7 messages to/from roaming partners. And from public RFPs, the US Department of Defense[5] runs their own private phone networks, with EAGLE STP at the core.
Given how prevalent EAGLE deployments were in the early 2000s, how SS7 is needed to make the phone network functional, and how STPs are fixtures that do NOT get swapped out often, I feel very confident in saying that Oracle has had a supporting hand in most, if not all, of the phone calls and text messages you've placed since 2013.
1: https://www.oracle.com/corporate/pressrelease/oracle-buys-te...
2: https://www.verizon.com/about/sites/default/files/2025-03-07...
3: https://www.verizon.com/business/content/dam/business-market...
4: https://www.lightreading.com/business-management/tekelec-win...
5: https://sam.gov/opp/2227eac9a05f7c33f25b19a6ed5ab634/view
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