# 1SIM VoIP

> Cost-effective international calls and texts via Wi-Fi/mobile data for existing customers. (iPhone/iPad app by Belmont Telecom, Inc..)

- Source: https://appshunter.io/ios/app/1sim-voip/id510371587 (this page in markdown: same URL + `.md`)
- Developer: [Belmont Telecom, Inc.](https://appshunter.io/developer/510353132)
- Category: Productivity, Travel
- Price: Free
- Rating: 4.36/5 from 78 App Store ratings · 29 written reviews indexed
- Age rating: 4+
- Requires: iOS 13.0 · 85 MB
- Languages: English
- Released: 2012-03-28
- Data updated: 2026-07-05
- Monetization: free
- User reviews in markdown: https://appshunter.io/ios/app/1sim-voip/id510371587/reviews.md

## What is 1SIM VoIP?

OneSim VoIP provides OneSimCard customers with an even less expensive way to make and receive international calls on their iPhone mobile phones or iPads. To use OneSim VoIP, users must have a good quality Wi-Fi, 3G, 4G or LTE Internet connection and a VoIP-enabled Personal Extra Number (PEN) activated with OneSimCard. When making an outgoing call, OneSimCard users can select the way the call will be made – either through the OneSimCard international SIM card or OneSimCard VoIP network. Calls made over the VoIP network are generally much less expensive than OneSimCard’s standard international roaming rates. Incoming calls made to the PEN will be received through low-cost VoIP if the OneSimCard phone and OneSim VoIP app are registered on the Internet. Otherwise, the call will be sent the usual way to the phone through the international SIM card. 

The newer version 2 of the app adds the texting feature and allows the sending and receiving  texts (SMS) to and from US and Canada mobile phones over Wi-Fi or mobile data at much lower rates than regular SMS sent and received over the roaming network. 

The app does not require having a OneSimCard SIM installed in the phone, but it does require having a OneSimCard account and a VOIP and SMS enabled PEN.

Initial settings for the app are available in the “My SIM Cards” menu of the OneSimCard online account. When in the My SIM Cards menu, select the SIM (if there are more than one on your account) and then click on the Create VoIP Account link. This will create a OneSimCard VoIP account and provide you with a link with Settings information for your iPhone or iPad. 

Important: Connection quality of the calls made using OneSim VoIP option over the Internet will only be as good as the quality of the Internet connection. Please be advised that in many cases this kind of connection quality is inferior to the connection quality made through the OneSimCard international SIM card roaming network.

## Key features

- Reduced international call rates
- Low-cost international SMS
- Wi-Fi and mobile data calling
- VoIP and SMS enabled Personal Extra Number
- Select call routing method

## Recent user reviews (10 of 29)

All indexed reviews: https://appshunter.io/ios/app/1sim-voip/id510371587/reviews.md

### 2/5 — So far, not so good

*2026-02-06, version 3.0.9*

Only been using it in UAE, maybe it has to do with the network here, but having a lot of trouble. The right service was trying to call me at at the airport, had all kinds of trouble taking their calls; no, I’m in a hotel room and I can’t load anything related to my account, such as checking how much data I have left, can’t even go to the side (OneSIM) e-store

### 4/5 — Calls and messages don’t always go through

*2025-07-15, version 3.0.9*

I’ve had several friends tell me they tried calling me but, after a couple of rings, they lost the connection. Meanwhile, I heard no ring and did not get a missed call notice.
Text messages also don’t always go through in either direction.

### 2/5 — Worst VoIP app I’ve ever used

*2025-02-07, version 3.0.9*

This app is a complete nightmare to use.The user interface is very complicated, when I allowed to contacts and call a number it called another number not related to the first one.The API requests and responses of this app show plane-text passwords and plane-text user IDs. The communication is unencrypted… Furthermore, I didn’t use the app for one week and 1Sim blocked my account. Now I have to pay more to use my account which has funds. Worst experience I ever at. Never using it again.

### 2/5 — Cannot receive calls

*2025-01-01, version 3.0.9*

Due to an iOS update you cannot receive a call unless you have the app open in the foreground.  Not useful to receive call when in the background.  Only useful for outgoing calls

### 5/5 — Great app. Saves money

*2024-10-14, version 3.0.9*

Have been using it for long time

### 1/5 — Works somehow but mot enough help.

*2024-09-20, version 3.0.9*

You should let people know that with some wifi signals it won’t log in or make any calls, on those cases a data connection is required. Need better customer support, too slow and difficult to make questions.

### 5/5 — Great app

*2024-07-18, version 3.0.9*

The updated SIM VOIP app works well.

### 5/5 — Big improvements

*2024-05-05, version 3.0.5*

This app was horrible and barely worked about a year ago. I recently tried it again and it has been working great for texting and calling. Considering cancelling my other service after I test it some more and make sure it’s reliable.

### 1/5 — Horrible

*2023-11-08, version 3.0.5*

It doesn’t work. System is unintuitive and poorly designed. Good luck getting tech support or customer service. There’s nothing like being in a foreign country and not being able to verify your card.

### 1/5 — Full of bugs

*2023-10-26, version 3.0.5*

Poorly designed app shows the wrong names on text and calls does not link properly with Contacts release prematurely should have been tested before pushing it to the App Store. Been a customer for three years not compatible load banks as they claim if you need a real number for verification we need one tie to your Social Security number with a real eSIM provider

## Frequently asked questions about 1SIM VoIP

### What does this app do?

This app provides a way for existing OneSimCard customers to make and receive international calls and send/receive texts at significantly lower rates than standard roaming. It utilizes Wi-Fi or mobile data connections to facilitate these communications, offering a more cost-effective solution for international communication.

### How do I set up the app?

To set up the app, you need an active OneSimCard account with a VoIP and SMS enabled Personal Extra Number (PEN). You can create a VoIP account and find the necessary settings information for your device within the 'My SIM Cards' menu of your OneSimCard online account.

### What are the costs associated with using this app?

The app itself is free to download and use. The cost savings come from the reduced rates for international calls and texts made through the app's VoIP network compared to standard international roaming rates. Specific rates are determined by your OneSimCard plan and enabled PEN.

### What are the requirements to use this app?

To use this app, you must have a good quality Wi-Fi, 3G, 4G, or LTE internet connection. Additionally, you need an active OneSimCard account and a VoIP and SMS enabled Personal Extra Number (PEN) activated with OneSimCard.

### Can I use this app without a OneSimCard SIM card?

Yes, the app does not require a OneSimCard SIM to be installed in your phone. However, it is essential to have a OneSimCard account and a VoIP and SMS enabled PEN to utilize the app's calling and texting functionalities.

## Version history (last 5 releases)

### 3.1.2 — 2026-05-14

- minor improvements

### 3.0.9 — 2024-07-17

- minor improvements

### 3.0.8 — 2024-07-01

- improved functionality

### 3.0.7 — 2024-06-22

- minor bugfix
- improvements

### 3.0.5 — 2023-10-23

- minor improvements

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## More apps by Belmont Telecom, Inc.

- [1Sim Connect](https://appshunter.io/ios/app/1sim-connect/id680700348)
- [1Sim Assist](https://appshunter.io/ios/app/1sim-assist/id862469463)
- [My OneSim](https://appshunter.io/ios/app/my-onesim/id1164159803)
- [1SIM IoT](https://appshunter.io/ios/app/1sim-iot/id1512993522)
- [1SIM eSIM](https://appshunter.io/ios/app/1sim-esim/id1531090410)

All apps by Belmont Telecom, Inc.: https://appshunter.io/developer/510353132

## Related topics

[onesim](https://appshunter.io/ios/topics/onesim)

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-07-05.*