# Basic Differences (PSTN & SoftPhone)

### The basic differences between PSTN & VOIP are:

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1. PSTN is the **sim-based** calling but VOIP is the **internet-based** calling.
2. PSTN supports only **domestic calls** whereas VOIP supports **both** domestic and international calls.
3. **Multiple DIDs** can not be accommodated in PSTN for outbound calls but in VOIP, multiple DIDs can be accommodated for **outbound calls**.
4. **Call Barging** is possible in both mediums.
5. **Call Transferring** and **Conferencing** are possible in VOIP but not in PSTN.

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Both types of **IVR** (PSTN and VOIP) are good at doing what they're supposed to do. They serve the **basic purpose** well. However, when it comes to more **advanced features**, they have some differences. 
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The choice between them depends on what the **client needs**. Clients should choose the one that **fits** their requirements better for their **subscription**.