Telephony
What is PSTN?
The PSTN, or public switched telephone network, is the worldwide system of carrier-operated landline and mobile telephone networks that lets any phone number call any other.
Also called: public switched telephone network, landline and mobile network, telco network
When a business calls a customer's mobile or landline, the call has to end up on the PSTN, because that is where ordinary phone numbers live. In India the carriers that run it include Jio, Airtel, Vodafone Idea and BSNL, and they are regulated by TRAI and the Department of Telecommunications. Software platforms usually do not own this network. They connect to it through a telecom provider, using a SIP trunk or a hosted number, and the provider hands each call to the carrier of the person being dialled.
Everything a voice agent does on a call ultimately has to pass through the PSTN, so the quality of that connection decides whether the phone rings, whether the caller's screen shows a trusted number and whether the call is billed. It is also where Indian rules apply: calling lines used for business outreach need DLT registration, and bulk campaigns must respect the Do Not Disturb registry. Outpero places calls from a DLT-registered +91 business number, so the agent reaches customers on the same network their own phone uses.
What is PSTN?
+
The PSTN, or public switched telephone network, is the worldwide system of carrier-operated landline and mobile telephone networks that lets any phone number call any other. When a business calls a customer's mobile or landline, the call has to end up on the PSTN, because that is where ordinary phone numbers live. In India the carriers that run it include Jio, Airtel, Vodafone Idea and BSNL, and they are regulated by TRAI and the Department of Telecommunications. Software platforms usually do not own this network. They connect to it through a telecom provider, using a SIP trunk or a hosted number, and the provider hands each call to the carrier of the person being dialled.
Why does PSTN matter?
+
Everything a voice agent does on a call ultimately has to pass through the PSTN, so the quality of that connection decides whether the phone rings, whether the caller's screen shows a trusted number and whether the call is billed. It is also where Indian rules apply: calling lines used for business outreach need DLT registration, and bulk campaigns must respect the Do Not Disturb registry. Outpero places calls from a DLT-registered +91 business number, so the agent reaches customers on the same network their own phone uses.
Related terms
Try it in 30 seconds
Hear your business’s fastest employee take a call
Call the agent yourself and hear how it handles a real enquiry in Telugu. No card, no signup — 50 free credits when you’re ready to deploy one.
No setup fee · calls from ₹5/min
Or see the full product — Andhra & Telangana's fastest employee.