Comparison of a Samsung Galaxy S6 unlocked by Japan's big three carriers

As expected, Softbank Mobile announced that it will also adhere to the new guidelines and begin unlocking phones brought new to market from this month. This includes the Samsung Galaxy S6 Edge. The terms are exactly like Docomo's: unlockable from 180 days after purchase until 90 days after the phone is disconnected. Unlocking within that 90-day window for an out-of-contract product will also require a trip to certain softbank stores and therefore cost ¥3,000 plus tax.

Unlocking terms by carrier

	KDDI	docomo	Softbank
Cost	Free (¥3,000+tax in store)	Free (¥3,000+tax in store)	Free (¥3,000+tax in store)
Applicable to devices released from	April 23, 2015	May 1, 2015	May 29, 2015
Wait time to unlock	180 days	6 months	180 days
Unlock possible after cancel service	forever	for 3 months	for 90 days

Galaxy S6 Edge Comparison

Right now, the only phone that will be unlocked by all three is the S6 Edge.

	KDDI	docomo	Softbank
Cost with MNP (without)	¥33,480 (¥55,080)	¥29,808 (¥58,968)	¥21,600 (¥53,760)
Earliest unlocking date:	October 20, 2015*	Now	November 25, 2015
Unlock cost	free	¥,3000	free
LTE Bands:	1, 3, 18, 26, 28	1, 9, 19, 21, "700"*	1, 3, 5
WCDMA (3G) Bands:	1	1, 5 (or 6?), ?	1, 5, 8

* The exact bands are ambiguous. docomo simply lists "700" which could be one of 12, 13, 14, or 17 or perhaps all may be covered because the frequencies are either adjacent or overlapping. Also, both KDDI and docomo list support for "800". KDDI specifically states this is band 18. I believe that docomo uses band 19. The uplink frequencies are overlapping and the downlinks are close but not adjacent.

Figuring out which bands are supported

KDDI is the only carrier clearly indicating this an in easy to understand way. Their bands are published here. Softbank's are on the product's specs page (SBM S6 Edge). Docomo's are also listed on the spec page, but only for LTE (DCM S6 Edge). To get the 3G bands is a real pain, but docomo will be required to make this more transparent once they release phones under the new guidelines.

Docomo classifies the S6 Edge as a "class 5 world wing" device, which looking up here gives contradictory information. The product pages lists LTE bands "2GHz, 1.7GHz, 1.5GHz, 800MHz, and 700MHz". However a class 5 world wing device supposedly supports LTE Band 1 (2.1GHz), Band 3 (1.8GHz) and "others" such as Bands 4, 17, 20 "etc" as well as "3G" (whatever the hell that means) and "3G850".

LTE（Band 1（2.1GHz）、Band 3（1.8GHz）、その他（Band 4、Band 17、Band 20など））および3G、3G850、GSMネットワークをご利用になれます。

I'm just guessing here, but since the most common 3G band (except in North America) is Band 1 (2100 MHz), I am guessing that "3G" refers to Band 1 and that 3G850 refers to Band 5 (Actually I'm told that what docomo calls "3G850" is actually Band 6). I also assume that it doesn't support AT&T's Band 2 (1900 MHz, aka PHS) or T-Mobile's Band 4 (1700/2100 MHz, aka AWS).

Digging ever deeper into docomo's i–mode-like labyrinth of a website confirms no support for 3G in North America.