I've been a T-Mobile customer for years. At one point, in response to an issue I had when my account was inadvertently changed by a store representative, I was given some sort of status where whenever I called in for support, I was routed to a higher level of support. Notice past-tense.
Over the years, I received outstanding tech support whenever I required it. In the last few months, suddenly, every tech support request (mostly for the same issue that never gets resolved), I been sent over to a call center in the Philippines. Before anyone accuses me of xenophobia, I was born in the Philippines and I speak the language fluently and I spend about 6 months of the year in Manila. I'm intimately aware of how things work in the Philippines.
The biggest problem is comprehension. As I do when I'm in the Philippines and ask a question at a mall or store for example, whether in English or Tagalog, it always takes two or more tries to get the person that I'm speaking to to understand what I need. When the issue is of a technical nature and there are no Tagalog equivalent words and it gets even more complicated. Compounding this are the inherent Filipino traits that they are super polite and genuinely don't want to disappoint you. Filipinos feel that saying "I don't know" means that they're not helping you. In their eagerness to help, the original message gets confused. This is a cultural thing that most Americans don't understand. To be sure, if Filipinos were to be routed to a call center in the United States, I'm certain that they would have the same issues as Americans calling Filipino call centers.
For example, in July (2018) I purchased two Apple Watches from a local store in San Diego. I discovered when I received my bill that my plan was changed and increased by $20 per month (apart from the increases due to the Apple Watches), and "free" Netflix was added. I called back to find out why, and I was told that I had requested the plan change. I didn't. It didn't make any sense to pay an additional $20 for something worth $10. The CSR, part of my "team" was at a call center in the Philippines. I was told that they would correct the problem revert back to the correct plan. The next time I got my bill, it wasn't changed. So I called again. I got the same "I will resolve your issues to you satisfaction, I guarantee it", but the next bill came around and it still didn't get corrected. So I called again. Still no resolution. Each call lasted more than 20 minutes. Upon arrival in San Diego a few days ago, I went to a store where they attempted to fix the problem. Still no resolution. So I called support again from San Diego and again I got a call center in the Philippines. I asked to get the call escalated, and I got... another person in the Philippine call center. The person I spoke to after being escalated had excellent command of English, and actually sounded American. However, she still had some issues understanding what I wanted and would ask me questions for which I'd already provided answers. Still waiting for resolution.
If it takes 4 or more tries to get resolution on an issue at a foreign call center and once at an American call center, I'm not sure that the cost savings involved in a foreign call center are worth it. Add to that the intangible cost of unhappy customers. Is it possible the T-Mobile bean counters don't take this into consideration?