# M System vs PrefixBlock

The clearest difference is in-app purchases: M System at none against PrefixBlock's 3. M System also leads on device support (3 vs 1) and iOS requirement (15.0 vs 17.6). PrefixBlock's advantage is update cadence (every 3 days vs weekly). On price and ads there is nothing between them.

Both are free to download. PrefixBlock sells 3 in-app purchases, starting at $0.99 per month. M System asks for nothing beyond the download.

M System ships an update weekly, PrefixBlock every 3 days. The most recent releases landed on October 24, 2026 and October 25, 2026 respectively.

## The numbers

| Metric | M System | PrefixBlock |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Weekly | **Every 3 days** |
| Size | 206 MB | 4 MB |
| Requires iOS | **15.0** | 17.6 |
| Devices | **iPhone, iPad, iPod** | iPhone |
| Age rating | 4+ | 4+ |
| Developer | [Vu Pham Anh](https://appshunter.io/developer/1674956591) | [Phung Doanh](https://appshunter.io/developer/965062916) |

## What reviewers say

### M System

[App page](https://appshunter.io/ios/app/m-system/id6445936927)

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases:** none


### PrefixBlock

[App page](https://appshunter.io/ios/app/prefixblock-spam-call-filter/id6800204952)

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Chặn đầu số pro tháng | $0.99 | per month |
| Chặn đầu số pro năm | $4.99 | per year |
| Chặn đầu số trọn đời | $9.99 | one-time |


## Frequently asked questions

### Is M System free?

M System is free to download, with no in-app purchases.

### Is PrefixBlock free?

PrefixBlock is free to download, with in-app purchases available.

### Do M System or PrefixBlock have ads?

Neither M System nor PrefixBlock shows ads.

### Which is updated more often, M System or PrefixBlock?

M System ships an update weekly, and PrefixBlock every 3 days. Most recently, M System was updated on October 24, 2026 and PrefixBlock on October 25, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*