# Callsling vs OneFill

The clearest difference is update cadence: OneFill at every 8 days against Callsling's every 2 months. Callsling's advantage is iOS requirement (13.0 vs 17.6). On price, ads, in-app purchases and device support there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

Callsling ships an update every 2 months, OneFill every 8 days. The most recent releases landed on October 2, 2026 and October 11, 2026 respectively.

## The numbers

| Metric | Callsling | OneFill |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[3.9 (7 ratings)](https://appshunter.io/ios/app/callsling/id1567538164/reviews)** | — |
| Number of ratings | **7** | — |
| Positive reviews | 66.7% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 2 months | **Every 8 days** |
| Monetization | Ad-supported | — |
| Size | 54 MB | 5 MB |
| Requires iOS | **13.0** | 17.6 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [Dan Klein](https://appshunter.io/developer/1567400747) | [Cassiel LLC](https://appshunter.io/developer/6776755032) |

## What reviewers say

### Callsling

[App page](https://appshunter.io/ios/app/callsling/id1567538164)

This app allows users to send and receive calls and SMS messages over WiFi. It provides call tracking capabilities, linking incoming calls to their source like SEO or websites. The mobile application integrates with a cloud-based system for advanced lead generation and call handling.

**Highlights:** Send and receive calls via WiFi, Send and receive SMS via WiFi, Track calls from SEO and websites, Configure new call tracking numbers, Lead generation call tracking, Advanced call handling

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

**In-app purchases:** none


### OneFill

[App page](https://appshunter.io/ios/app/onefill-pro/id6783223969)

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

**In-app purchases:** none


## Frequently asked questions

### Is Callsling free?

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

### Is OneFill free?

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

### Do Callsling or OneFill have ads?

Neither Callsling nor OneFill shows ads.

### Which is updated more often, Callsling or OneFill?

Callsling ships an update every 2 months, and OneFill every 8 days. Most recently, Callsling was updated on October 2, 2026 and OneFill on October 11, 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.*