Network wise pretty similar, so are the outages.
Here are some known difference for you :
Vivifi & Zym doesn't supports VoWifi, Zero1 has previously claimed VoWifi support, but later denies that. User feedback is that it doesn't work, except a single report of it working.
Zym don't have esim so far, zero1 & vivifi has.
Zym requires an app to do any management, zero1 & vivifi can use web page.
Zero1 has least talk time for plans >=$10, Vivifi has more and zym has even more.
Zym requires
IDD add-on plan to call IDD,
Zero1 &
Vivifi is pay per use.
Vivifi supports number port anytime, zero1 submit at application, zym submit at activation.
Vivifi seems to have a reputation to get the name order mix up resulting in porting problems.
Physical sign up : Zero1 at
Harper Point, Vivifi have a
few, zym has
lots.
Zym send bill by 5th/deduct on 10th, zero1 send bill on 6th/deduct on 8th, Vivifi sends ard 25th.
All 3 use calendar month billing cycle.
For the cheapest plan Zero1 is $7.06, Vivifi $7.70, Zym $7.77. The 2 other popular plans Zero1 & Vivifi is the same, Zym is $0.10 more.
Zym's $10.10 plan provides free 5G for 180 days.
Vivifi has 2 different $15 plans, most should prefer the more recent "Roam Asia Super 5G" plan. Note the other plan "Roam MY Super" only includes 5G for 12 months.
For port in Zym & Vivifi can use with temp no. once activated, Zero1 doesn't provide temp number & needs to wait for port in (including esim, totally no connection before port in is complete, Also sim pick up on Fri-Sun can only activate next business day after 2pm.)
For port out Zym just have to be done by end of month, Vivifi appears to be the same, for Zero1 I can't find anything but there are reports of billing after port out so there might be a notice period there.
For termination Vivifi/Zero1 both ask for 7 day's notice (Zero1 by 3pm), Zym did not specify.
Port back :
Zym - promo doesn't apply for numbers that was with Zym in the past 12 months
Zero1 - if number was with Zero1 in the past 3 Months, there is a one-time registration fee of $10.90 + $5.45 for the cost of the SIM card.
Change of plan :
Vivifi - 5 business days (no longer charge, prorate, lose existing discount),
zero1 - 7 business days ($10.90 for downgrade, prorate, subsequent change a month later),
zym - 5 working days (no longer charge for downgrade, prorate, lose any promotional benefits)
Minimum subscription :
Vivifi - 2 bills (2 months + any prorated part of a month)
Zero1 - 1 month+7 day's notice (b4 3pm) if that exceed the billing cycle, another month will be billed.
Zym - 2 months
