You are correct in that TMO doesn't have coverage in Vietnam and Sprint now does. As you mentioned TMO has had this "locked out", well not really locked out since the other carriers could have done this 2 years ago when T-Mobile did it but didn't want to give up that huge revenue source with the exorbitant fees and rates they charged to use it. Of course the carrier(s) in that country have to come to some kind of agreement and as they say it takes 2 to tango. Now in your case if Vietnam is a country you travel to often then yes right now Sprint may be the better option. However to say their international coverage is better?? eh if Vietnam and a few other countries is you measuring stick then maybe but also look at that TMO doesn't even consider Mexico or Canada as international yet Sprint charges you for those unless you are some premium plan they offer.
The problem here is that the carriers will always be trying to "one up the other" so you could jump to Sprint today but tomorrow TMO could offer something that is even better and now you stuck with an inferior network here in the US. Not to mention TMO has a much better record of launching new things the customers want and/or need and it took Sprint how long to launch this after TMO did? 2 years..... I suspect TMO would have an agreement in Vietnam if the local carriers(s) wanted one or they are wanting way too much money for one which make it financially not feasible to add it.
Hey there magenta2929453 .
We definitely don't want you to switch but we do wanna make sure you have everything you need on what plans we do offer. I do hope you weigh your options before you make a decision. We'd rather stay with us but only if we can give you all the services that are important to you.