Need Answer for technical Question
 

Am ready to buy a Data SIM card when I land overseas. Will get country specific one(s) since as was pointed out to me in other thread - they are VERY cheap as compared to intl. SIMS.

The ones I am looking at all seem to have the following language:

"Data and text only on this card, no voice or roaming."

I know that Data SIMS here in U.S. can not be used in phone and a phone SIM can't be used in Data device.
Can I assume that while I can't directly use this for voice - IF I set up a wifi hot spot with my data device, can I make calls via wifi? (T-Mobile has free wifi calling to the U.S. built into most of their phones.) Or is there some way the SIM could block this as well as Skype calls etc.?

Hi.

Generally, all European data SIM cards or "data-only" plans work in all GSM devices: smartphones, routers, moderm, Mifis, tablets ..... They are targeted at tablets and modems. So there is absolutely no problem to use it in a modem creating a WIFI hotspot (Mifi router). But you can use it in smartphones too, only without (regular) voice calls and sometimes texts. It is even easier sometimes to book a data-only package through a phone by USSD code than to navigate on personal online accounts on the web in foreign languages.

Whether the specific provider allows VoIP calls is a totally different story. T-Mobile in the US actually pushes Skype, while the same company in Germany on its home network actively blocks it. The telcos (or cellcos) don't like VoIP so much over here :-)

There are 3 attitudes:
- banning VoIP calls by blocking the respective ports (this is rare, but happens)
- banning VoIP calls in their T&Cs only - with no consequences for the user at all, you can still use it
- allowing VoIP - which is the most common and widespread in the countries you visit.

So for Skype or other VoIP, you better ask in the shops of the operator when you buy your local SIM card, as their policies sometimes change. But normally, you can go ahead. For a decent Skype call, you should have a stable 3G or WIFI connection. That's why you should prefer one of the bigger networks on the list to the smaller (and often cheaper) ones.

Wolfbin -
Thanks for your detailed reply.
One "error". TM, in the U.S., actively pushes the fact they have wifi calling built in to the phone and their system. They didn't very actively promote it for years - but the last 6 months have done that. TV ads show you can make phone calls deep within your basement where cell signals don't penetrate as long as you have wifi.
Skype is never mentioned directly by TM or any other carrier.

I don't know if using TM's built in wifi calling would be blocked like a Skype call would. Probably would. Glad you pointed out I should try and determine if a particular data card allows for voip calls. I'd need to buy card in a company store to get that answered.
Probably, since the data SIMS are so cheap, and you said most will allow voip, I'll just take a chance.