Zym mobile roam smart 5G SIM only plan

[SESE75]

Very Disappointing Experience with ZYM Mobile – Please Think Twice
I would like to share my horrible experience with ZYM Mobile, in hopes of warning others who may be considering switching.
I came across ZYM’s Roam Smart 5G Plan, which sounded extremely attractive — 400GB local data, 2,000 outgoing calls, unlimited incoming calls, free Caller ID, 100 SMSes, 20GB roaming data for several Asian countries, and an additional 600GB roaming data for one year covering Malaysia, Indonesia, and Thailand. On paper, this looked like excellent value.
My daughter was previously on an M1 SIM-only plan, paying about $24 per month (including $5 for Caller ID). I thought this would be a good opportunity to switch telco for her while retaining her existing M1 number.
Unfortunately, this is where the nightmare began.
On 6 January 2026, I signed up for the Roam Smart 5G plan at ZYM’s JEM outlet, made an upfront payment of $27 (presumably covering January and February), and collected the SIM card. I was advised to continue using the existing M1 SIM until there was “no service”.
On the morning of 7 January 2026, the M1 SIM showed “No Service”, so my daughter switched to the ZYM SIM. That’s when we discovered a serious issue:
Calls to her number returned the message “The M1 number you are calling is not in use”
This happened not only for her original M1 number, but also for the temporary number issued by ZYM
My daughter could make outgoing calls and use mobile data
However, my wife and I (both M1 users) could not reach her at all
We tried reinserting the SIM card, restarting the phone multiple times, and testing repeatedly — nothing worked.
Things got worse when I contacted ZYM customer support via WhatsApp at +65 8090 0000. The automated reply stated a 4–8 hour waiting time for a live agent. I messaged repeatedly over the weekend and received the same automated response every time, with no human assistance at all. This was incredibly frustrating and unacceptable.
On 9 January 2026, I went back to the JEM outlet with my daughter. The salesperson confirmed that only M1 users were unable to get through to her line, and informed us that the issue had to be escalated to their backend team. No immediate solution was provided, and we were simply told to wait.
Left with no choice, we could only rely on WhatsApp calls to stay in contact.
Moral of the story:
If you are considering switching to ZYM Mobile because of its attractive bundles, please think twice. ZYM is a third-party MVNO using Singtel’s network, and based on my experience, they lack the capability, experience, and support infrastructure to properly handle or resolve serious port-in issues.
This entire experience has been extremely disappointing, frustrating, and stressful.

You have been warned.

 

[chari-men]

Very Disappointing Experience with ZYM Mobile – Please Think Twice
I would like to share my horrible experience with ZYM Mobile, in hopes of warning others who may be considering switching.
I came across ZYM’s Roam Smart 5G Plan, which sounded extremely attractive — 400GB local data, 2,000 outgoing calls, unlimited incoming calls, free Caller ID, 100 SMSes, 20GB roaming data for several Asian countries, and an additional 600GB roaming data for one year covering Malaysia, Indonesia, and Thailand. On paper, this looked like excellent value.
My daughter was previously on an M1 SIM-only plan, paying about $24 per month (including $5 for Caller ID). I thought this would be a good opportunity to switch telco for her while retaining her existing M1 number.
Unfortunately, this is where the nightmare began.
On 6 January 2026, I signed up for the Roam Smart 5G plan at ZYM’s JEM outlet, made an upfront payment of $27 (presumably covering January and February), and collected the SIM card. I was advised to continue using the existing M1 SIM until there was “no service”.
On the morning of 7 January 2026, the M1 SIM showed “No Service”, so my daughter switched to the ZYM SIM. That’s when we discovered a serious issue:
Calls to her number returned the message “The M1 number you are calling is not in use”
This happened not only for her original M1 number, but also for the temporary number issued by ZYM
My daughter could make outgoing calls and use mobile data
However, my wife and I (both M1 users) could not reach her at all
We tried reinserting the SIM card, restarting the phone multiple times, and testing repeatedly — nothing worked.
Things got worse when I contacted ZYM customer support via WhatsApp at +65 8090 0000. The automated reply stated a 4–8 hour waiting time for a live agent. I messaged repeatedly over the weekend and received the same automated response every time, with no human assistance at all. This was incredibly frustrating and unacceptable.
On 9 January 2026, I went back to the JEM outlet with my daughter. The salesperson confirmed that only M1 users were unable to get through to her line, and informed us that the issue had to be escalated to their backend team. No immediate solution was provided, and we were simply told to wait.
Left with no choice, we could only rely on WhatsApp calls to stay in contact.
Moral of the story:
If you are considering switching to ZYM Mobile because of its attractive bundles, please think twice. ZYM is a third-party MVNO using Singtel’s network, and based on my experience, they lack the capability, experience, and support infrastructure to properly handle or resolve serious port-in issues.
This entire experience has been extremely disappointing, frustrating, and stressful.

You have been warned.

Not only zym.. this is a Heng suay kinda thing.. quite a few have encountered similar issues porting to simba.. giga and other mno or mvno as well.. usually porting out to other telcos will solve this issue.. root cause of this is due to blackened didn't not port in your daughter's number 100% ... Some things were left out ...

 

[gapboy]

Dont see a need for a new thread for ranting.. complaining here won't resolve anything too..

99% wont have such issue only the unlucky ones which is unavoidable happens anywhere

 

[Tedicious]

Very Disappointing Experience with ZYM Mobile – Please Think Twice
I would like to share my horrible experience with ZYM Mobile, in hopes of warning others who may be considering switching.
I came across ZYM’s Roam Smart 5G Plan, which sounded extremely attractive — 400GB local data, 2,000 outgoing calls, unlimited incoming calls, free Caller ID, 100 SMSes, 20GB roaming data for several Asian countries, and an additional 600GB roaming data for one year covering Malaysia, Indonesia, and Thailand. On paper, this looked like excellent value.
My daughter was previously on an M1 SIM-only plan, paying about $24 per month (including $5 for Caller ID). I thought this would be a good opportunity to switch telco for her while retaining her existing M1 number.
Unfortunately, this is where the nightmare began.
On 6 January 2026, I signed up for the Roam Smart 5G plan at ZYM’s JEM outlet, made an upfront payment of $27 (presumably covering January and February), and collected the SIM card. I was advised to continue using the existing M1 SIM until there was “no service”.
On the morning of 7 January 2026, the M1 SIM showed “No Service”, so my daughter switched to the ZYM SIM. That’s when we discovered a serious issue:
Calls to her number returned the message “The M1 number you are calling is not in use”
This happened not only for her original M1 number, but also for the temporary number issued by ZYM
My daughter could make outgoing calls and use mobile data
However, my wife and I (both M1 users) could not reach her at all
We tried reinserting the SIM card, restarting the phone multiple times, and testing repeatedly — nothing worked.
Things got worse when I contacted ZYM customer support via WhatsApp at +65 8090 0000. The automated reply stated a 4–8 hour waiting time for a live agent. I messaged repeatedly over the weekend and received the same automated response every time, with no human assistance at all. This was incredibly frustrating and unacceptable.
On 9 January 2026, I went back to the JEM outlet with my daughter. The salesperson confirmed that only M1 users were unable to get through to her line, and informed us that the issue had to be escalated to their backend team. No immediate solution was provided, and we were simply told to wait.
Left with no choice, we could only rely on WhatsApp calls to stay in contact.
Moral of the story:
If you are considering switching to ZYM Mobile because of its attractive bundles, please think twice. ZYM is a third-party MVNO using Singtel’s network, and based on my experience, they lack the capability, experience, and support infrastructure to properly handle or resolve serious port-in issues.
This entire experience has been extremely disappointing, frustrating, and stressful.

You have been warned.

No issue for me when I port to zym. Ts u just sway lo. Can happen to anyone and any telco not just zym

 

[Apex]

This is what we usually get when we sign up with an MVNO. Porting your number is basically a gamble you’re just hoping nothing breaks.

MVNO support teams are usually very small, so support can be hit or miss, often more miss than hit. It sometimes feels like agents cherry-pick the easy tickets and ignore the rest.

That said, there are some MVNOs that provide pretty good support. I once had a port-in issue and emailed support on a Saturday morning. I was surprised that someone responded and fixed it by the evening. That was about three years ago, though, so I’m not sure if they’re still maintaining that level of service.

If you want consistently reliable support, it’s safer to stick with one of the big three telcos.

 

[ChungMuro]

Ok can, noted.

 

[gapboy]

This is what we usually get when we sign up with an MVNO. Porting your number is basically a gamble you’re just hoping nothing breaks.

MVNO support teams are usually very small, so support can be hit or miss, often more miss than hit. It sometimes feels like agents cherry-pick the easy tickets and ignore the rest.

That said, there are some MVNOs that provide pretty good support. I once had a port-in issue and emailed support on a Saturday morning. I was surprised that someone responded and fixed it by the evening. That was about three years ago, though, so I’m not sure if they’re still maintaining that level of service.

If you want consistently reliable support, it’s safer to stick with one of the big three telcos.

it is a 50-50 % issue can happen to MNO too .. When there was no MVNOs last time MNO is the major player .. Porting is done on back end regardless it is virtual or not.

The only issue is the MVNOs have limited support due to the pricing factor which is already known before anyone sign up.

 

[skazzz]

Porting, as many have mentioned, can be hit or miss. It doesn’t happen often, but it’s still possible.

Even if you’re paying a higher rate with the main provider, these issues can occur. The difference with MVNOs is that they usually lack direct support—any problems ultimately get escalated back to the primary provider, since MVNOs have limited control.

When it comes to porting, it’s generally considered normal. In fact, it’s a relatively minor issue compared to the bigger problems that providers sometimes leave unresolved for months. At that point, the only way to fix things is to leave their service entirely and switch to a new provider.

 

[jeffyap78]

I am a m1 user for more than 10 years since their launch. 2 years ago i ported five lines over to zym, no issue. After a year or so, i ported from zym to redone due to Challenger's 50% promo. After finished that four months 50%,i ported back to zym,no issue also. Now the only issue i faced is zym system captured that i have 10 lines with them and i cannot sign the 6th line,so i signed up with Eight because i found a nice number,and now port from Eight to Cmlink because to 6 months of 50% discount.

 

[xiaofan]

This is what we usually get when we sign up with an MVNO. Porting your number is basically a gamble you’re just hoping nothing breaks.

MVNO support teams are usually very small, so support can be hit or miss, often more miss than hit. It sometimes feels like agents cherry-pick the easy tickets and ignore the rest.

That said, there are some MVNOs that provide pretty good support. I once had a port-in issue and emailed support on a Saturday morning. I was surprised that someone responded and fixed it by the evening. That was about three years ago, though, so I’m not sure if they’re still maintaining that level of service.

If you want consistently reliable support, it’s safer to stick with one of the big three telcos.

Well said.

Personally I stick to SingTel SIM Only S$15.28 plan (recontract offer, with 12 months contract) as my main line.

Then I use eight S$8 plan as a secondary line and also for roaming usage.

For MVNOs, it seems to me M1 Maxx 1693 hotline support is not bad based on my experiences. CMLink and CUniq have hotline support as well.

 

[KosmoKramer]

To minimize this kind of issue when porting to zym, my guess is to avoid porting when the backend system is overload, maybe avoid during promo period or the first 10 days of the month when the backend is preparing customer bills, I notice that zym app is sluggish during billing day.

 

[froztheart]

In summary - unlucky.
Those that frequently port in and out anywhere has chances of facing such issues when the MVNO/MNO's Backend team misses/screws up somewhere somehow.
Contact the support and escalate to IMDA whenever needed, of course make sure that your own documentations etc. are accurate and correct first.

 

[Swayer]

I ported my secondary M1 SOP line to ZYM Roam Smart 5G on 30 Sep 2025(last day of the FOC SIM) with 6 mth Free promo. IIRC, it took about 2-3 days before the M1 number was ported over without any issue. Initially, just have to use the tempoary number. I guess it's a hit or miss. Hope you issue will be resolved soon.

 

[Charlie_Zhan]

hope our resident harry porter can come in to provide his vast experience and insights.

 

[gapboy]

hope our resident harry porter can come in to provide his vast experience and insights.

haha i remembered he has porting issue too 1-2x forgot which telco too many to remember

 

[maxheadroom]

Porting from VIvifi to M1. Family of 7
Mainline port successfully, but my family member all mobile been cut off (Not transfer successfully). After spoken the the Techincal backend support, they tell me to tell m1 the name is wrongly input with a spacing. Took the next run of job next day, and the transfer is successfully

 

[natas]

Happened to me last Nov when I ported M1 to ZYM. Took 10 days... extremely difficult to get support but this is the price of going cheap n guess the authority dun define KPI on support.

 

[crystalnox]

Can happen with any telco when porting la, I had something similar happen to be 2 years back with Giga -> CM-Link. At least your daughter still had data, my number disappeared into a black hole for a few days.

 

[Mancunian2]

the whole saga is best summarised by this diagram

 

[crystalnox]

the whole saga is best summarised by this diagram

This situation falls into the outside grey area, which should be labelled "just suay".