Justin S.
One of the most frustrating apps I've…
One of the most frustrating apps I've ever had the displeasure of using. NOTHING works on the iOS app. COMPLETELY horrible design and implentation, incredibly frustrating.

SLYNUMBER is the easiest way to add a second mobile number to your phone - no SIM card or new device is needed.
SLYNUMBER (slynumber.com) has 84 customer reviews on Five Star Index, with an average rating of 3.2 out of 5.
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Computers & Phones · Somerville, Massachusetts
Excellent

Computers & Phones · Natick, Massachusetts
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Computers & Phones · Boston, Massachusetts
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Computers & Phones · Cambridge, Massachusetts
Excellent
Showing 36 reviews with 1 star · Clear filters
Justin S.
One of the most frustrating apps I've ever had the displeasure of using. NOTHING works on the iOS app. COMPLETELY horrible design and implentation, incredibly frustrating.
Mino G.
The app is down since last night - can't sign in and I can't sign in even on my computer to see what's going on. I have messaged customer service 5 hours ago and still no answer. Clearly, they don't have a 24-hr customer service so if their service is down, you don't have a phone service until they report back to work! This is not the first time it happened!
Jeff S.
SO MUCH REGRET Several years after signing up for this service, they are now refusing to port out the number, coming up with arbitrary excuses. I have duplicate charges, with documentation that they refuse to rectify, support just doesn't even reply. Basically a scam/fraudulent company that should be shut down. They're overbilling, refusing port outs... I thought we got control of these scam telecom companies. FCC asleep at the wheel. They have no phone number listed on their website, terms of service, clearly they are used to ducking and avoiding accountability. Look hard for a way to contact them before you sign up, they only have an email inbox they they ignore. SUPER SHADY ORGANIZATION HERE
Response from SLYNUMBERJul 11, 2025
I am not sure who this customer is since they did not leave any information. We are not a shady organization. We allow people to port out their number. It is in our terms of service: https://slynumber.com/terms.html The user whoever you are please reply with the email you have sent our support that justifies your review.
AL
The product description clearly states: “The best part of all is it is a true mobile number. Meaning, you can activate services with it like PayPal, Facebook or WhatsApp.” However, upon using the service, I found that the number provided is being recognized as a VoIP number and was rejected by PayPal and other services for verification purposes. To make matters worse, I requested a refund by email in accordance with the 24 hour refund policy stated on their website. However, the developer refused to refund me and eventually started ghosting my emails. There are many similar reviews. it is truly a malicious service. Please DO NOT waste your money. Edit If you have time to respond to this review, I think you would be better off using that time to respond to your customers' emails.
Response from SLYNUMBERJun 24, 2025
Our numbers are classified as real mobile (non-VoIP) numbers at the carrier and network level. However, third-party platforms implement their own internal validation rules and filtering mechanisms, and they reserve the right to approve or reject any applicant at their sole discretion. This may impact whether a number is accepted or fully functional on certain services. All users can check on this link: https://www.npanxxsource.com/wireless-block-lookup.htm As we have said third party platforms reserve the right to accept or reject applicants. This is especially true for financial platforms as they are subject to tight regulations. We have thousands of customers that use us for Paypal, Facebook and WhatsApp. If the user had contacted us we will work with them to address the issue. We are not a scam and we stand behind our product. We offer support and the user always is welcomed to contact us.
Shoda S.
The service doesn’t deliver what it promises. Worse, when you try to cancel, the app and the website crash at the cancellation step — every single time. This isn’t incompetence; it’s a calculated move to keep customers trapped. It’s abusive, dishonest, and should be illegal. Do not give this company your money.
Response from SLYNUMBERJun 27, 2025
We provide support. If the user has encountered an issue while canceling we provide the support. This user account was actually canceled even though the web application crashed. There is no malicious intent behind this
Cam
They never canceled our billing, even after getting confirmation that it was canceled.
Ernie N.
This site is a scam. Once you sign up It is impossible to cancel. I had to cancel my credit card and get a new number for them to stop charging me!
Stephen S.
SLYNUMBER claims that their phone numbers are real Mobile Numbers, DON'T BE FOOOLED their phone numbers are straight up VIRTUAL NUMBERS, SLYNUMBER has the following message right on their website. "Google Voice, Burner, Hushed, Sideline, Phoner, Ding Tone, and Text Free offer VoIP numbers that come with numerous limitations and are currently rejected by many online services and apps. SLYNUMBER is the only mobile app on the market to offer REAL MOBILE NUMBERS No SIM card is required. Just call them LYNUMBER because their phone numbers are VIRTUAL NUMBERS, I purchased a 3 month package and I tried using the number with Cash App & WhatsApp and both times the LYNUMBER was rejected and denied, I received a message from both Cash App & WhatsApp saying they do not accept virtual numbers. And when I emailed LYNUMBER 3 hours after making the purchase well within the first 24 hours of the purchase (which is what their refund policy states must be done in order to receive a refund) they tried telling me that my refund request was not within the 24 hour window that is stated on their refund policy after I knocked that excuse down, they decided to question my truthfulness, Rather then refunding my card as I asked them to do, They offered me the opportunity to change and replace the number I originally chose when I established the account. I decided to give LYNUMBER a chance to redeem themselves, Now remind yourselves they knew the first number did not work with Cash App or WhatsApp, So you'd think that they would make sure the number they were switching me to would work no questions asked on apps like Cash App or WhatsApp...... The new number they gave me, DID NOT TEXT AT ALL.. THE NUMBER DID NOT WORK PERIOD. SOO, DON'T WASTE YOUR TIME WITH LYNUMBER THESE GUYS ARE CROOKED & MISLEADING. You won't be happy,