Just went back from Cancun. Used 1st SIM with UltraMobile (a T-mobile MVNO) and 2nd SIM with Project Fi (data only). UltraMobile doesn't offer any king of data while roaming, voice and SMS only.
Enjoyed both services with absolutely no problem. Identical combination worked fine all over Europe late June this year.
NOTE: I couldn't activate wifi-calling through hotel's wifi. Viber, Whatsapp, etc. worked fine on SIM2.
Hope this help.
Answers
Not when a CDMA SIM is in use in slot 1. But with two GSM SIMs, yes.
Just went back from Cancun. Used 1st SIM with UltraMobile (a T-mobile MVNO) and 2nd SIM with Project Fi (data only). UltraMobile doesn't offer any king of data while roaming, voice and SMS only.
Enjoyed both services with absolutely no problem. Identical combination worked fine all over Europe late June this year.
NOTE: I couldn't activate wifi-calling through hotel's wifi. Viber, Whatsapp, etc. worked fine on SIM2.
Hope this help.