Communications

VoIP vs PSTN — Phone System Comparison for Indian Businesses 2026

PSTN (Public Switched Telephone Network) is the traditional copper-line phone system — physical wires, dial tones, geographic limitations. VoIP (Voice over IP) carries voice as digital packets over the internet — flexible, software-based, internet-dependent. For Indian businesses, VoIP is increasingly replacing PSTN due to cost, flexibility, and feature advantages.

PSTN uses dedicated copper or fiber lines for each phone — reliable but inflexible. Adding lines requires physical installation. VoIP uses internet for call transmission — calls between VoIP users are essentially free; calls to/from PSTN numbers route through gateways. India's telecom regulator (DoT) requires VoIP-based call centers serving Indian customers to register as Other Service Provider (OSP). VoIP business benefits: cheaper international calls, easy add/remove of extensions, mobile/desktop integration, advanced features (IVR, ACD, recording, analytics) at fraction of PSTN cost. Modern cloud PBX (Exotel, Knowlarity, Zoom Phone, Microsoft Teams Phone) is VoIP-based.

Industries served: Call centres, BPO, Customer support, Sales teams, Multi-branch businesses, Remote / distributed teams

Related terms: Cloud PBX, SIP Trunking, IVR, Call Center, Zoom Phone, Microsoft Teams Phone

Frequently Asked Questions

Is VoIP cheaper than PSTN for Indian businesses?

Usually significantly cheaper. PSTN basic business line: ₹500-2,000/month rental + per-minute charges (₹1-3/min for outgoing). VoIP via cloud PBX: ₹500-1,500/month per agent including unlimited internal calls + cheaper external calls (₹0.50-1/min STD). For 10-agent call centre, VoIP saves ₹30,000-1 lakh/month vs equivalent PSTN setup.

Do Indian businesses need DoT OSP registration for VoIP?

Yes if you provide voice services to customers (call centre, BPO operations). OSP registration: DoT website, free application, typically approved in 30-60 days. Required documentation: company registration, business plan, network diagram. Without OSP registration, running a VoIP-based customer call centre is non-compliant. For internal-only VoIP (employees calling each other), OSP registration is not required.

What is the quality difference between VoIP and PSTN in India?

Modern VoIP on stable internet (50+ Mbps leased line, low jitter, low packet loss) is comparable to PSTN — sometimes better (HD voice codecs). On unreliable internet, VoIP quality degrades noticeably (jitter, latency, dropped calls). For Indian businesses, VoIP works best with: dedicated leased line (Tata, Airtel, Jio), QoS configured to prioritise voice traffic, backup connection for reliability.

Can I keep my existing phone numbers when switching to VoIP in India?

Yes via Mobile Number Portability (MNP) or DID porting. India supports number portability for landline and mobile numbers. VoIP providers like Exotel, Knowlarity, and others handle the porting process — typically 7-15 business days. During transition, you can run both PSTN and VoIP in parallel.

Should small Indian businesses use VoIP or stick with PSTN?

For under 5 phone lines: PSTN basic landlines may be simpler. For 5+ extensions, multi-location, or call centre needs, VoIP is dramatically more cost-effective and feature-rich. Modern recommendation: Microsoft Teams Phone or Zoho Voice (bundled with productivity suites) for small business needing 5-25 extensions, cloud PBX (Exotel, Knowlarity) for dedicated call center needs.

Free VoIP migration for Indian businesses — cloud PBX setup + OSP registration support.