The fact that the voice sounded foreign isn't a giveaway that it's a scam call. Many CS reps are outsourced to other countries.
I contacted Spectrum Cable last week to change my cable package. The first person I spoke to have a very, very heavy foreign accent. I could barely understand her. When I called back a couple days later with a question, the person I spoke to didn't have any accent at all.
But the fact that they were even calling to tell you they were doing upgrades is a giveaway. When my cable company is going to do something like that, it is always in writing, never a phonecall. Can you imagine having to call every subscriber/customer? LOL