Hi all. I am wondering if there is a SIM that can be purchased that will give data access across Asia, or at least a fair bit of Asia? I sick of carrying many SIMs just to be used for 1 or 2 days in each country.

Any ideas? Thanks.

None of the prepaid Asian network provide reasonably priced plans that let you roam. Only option is TMO

I've been using this service since it came out a couple of years ago, and it works great.

KnowRoaming

Very limited Asian covered countries.

If you're from the US, this is a good way to go.

I generally rely on T-Mobile's international roaming, but my phone is fully unlocked so sometimes I'll pick up a local SIM if I'm in a country for more than a few weeks in order to get better speed.

Not sure where you're based, but some places such as Hong Kong, have roaming data plans where you pay by the day for unlimited (128kbps after 300MB) data roaming for over 50 countries. Not that expensive (~9USD/day).

You might want to check to see if something similar is available from your carrier?

I can understand the OP wanting to see if there is a single sim for Asia to make it more convenient for multiple countries/short stays, but as mentioned above these don't exist yet [at least not in a cost effective option]

In the current era of dual sim phones, its a no brainer for me to keep my primary sim in one slot, and purchase a local sim for each new destination in Asia [no matter how short the trip]
Local data plans are just so much cheaper on a day to day basis than any roaming charges [whether from the home country/primary sim or a global/travel/roaming sim]

For the inconvenience of purchasing these local sims, the cost and benefits [data plans] outweigh the stuffing around.

It hasn't been mentioned yet in this thread - but perhaps the introduction of the AEC will in future produce a multi-country option for a SE Asian telco sim which provides what the OP is after. But at this time, unfortunately not.

OP - can you provide a quick run down of the countries you are visiting and the duration of stay in each? Might help us to swing some options your way...

It's more than just a convenient sim card - mobile carriers/mnvo in different Asia countries (and, elsewhere) adopt different standards & frequencies/bands, including HSPA+ and 4G/LTE (saw "5G" symbol on my Nexus device late last year in South Korea) - depending on your device's hardware, it should work and sometimes / often - it might NOT work without some configuration tweaks, etc. etc.

Sold/traded up one of our two Nexus 5 for the newest Nexus 5X to pickup more bands for travel, but not going to chase coverage by "retiring" the backup iPhone 5S for the next iPhone 7 or whatever.

I had a dual Sim phone a few years, first generation smartphone and might be going back to that scheme - one of the newest BLU might just be the ticket - and, going to play more possibilities with Project Fi (Google) since the N5X is the ideal platform for it - too impractical for the phabet N6 or N6P, as a matter of personal preference.