they hung up after 2 rings.

The callers are Vietnamese girls trying to steal your identity.  If you call them back, then they would hang up.  Thus, they know that you exist.
The next step that they would do is to forward all your mails to one of their mail addresses.  Here are two of their addresses:

9851 BOLSA AVE, SPC #163, WESTMINSTER, CA  92683

8742 STANFORD AVE, APT 4, GARDEN GROVE, CA  92841

Both addresses are in Vietnamese community.

Once they receive your forwarded mails, they would try whatever they can to gather much information about you from your mails, such as credit card numbers.  Then they would go shopping using your information or sell your information to others.

Keep getting calls from this number in a foreign language

Left a message in Vietnamese.  Have been getting these phone messages for a while now- at least a few months, but from different numbers.  I called them back and the customer service has a strong accent, but speaks English.  I said not to call me anymore- we'll just wait and see now.

Left a message in Vietnamese.  I've been getting these phone messages almost daily (but from different numbers) for the past month.