Considering revenue loss to local PSTN service providers in a region, VoIP to PSTN is still not allowed over WAN. There has been various discussions so far on this subject viz what is allowed and what is not allowed. In absence of clearly defined regulations considering all use cases, there is bit of chaos on the subject.
In the nutshell as per TRAI, no call routing should happen which is not in the interest of PSTN service provider with respect to toll bypass.
TRAI regulates that IP to PSTN calls are not allowed as long as it bypass the toll otherwise it's allowed.
Allowed Cases:
1. Call between two VoIP phones in same or different geographical locations
If there are offices in New Delhi and Mumbai, calls made from IP phone to IP phone between these two offices are allowed.
There is no geographical restriction to this scenario. If one office is in India and other is in San Jose, still such calls are allowed as long as calls are originated from and terminated to IP terminal.
2. Call from VoIP phone to a PSTN gateway in same geographical location
If there are offices in New Delhi and Mumbai, each site should have local PSTN gateway. Calls originated from New Delhi IP phones must use the PSTN gateway installed within New Delhi office. Same is applicable for calls originated from Mumbai office.
Incoming calls to New Delhi PSTN gateway must be routed to IP phones within office premises. Same is true for incoming calls to Mumbai PSTN gateway.
Needless to say, TEHO scenarios are restricted.
Not Allowed or Restricted:
1. Call that passes through PSTN gateway connects directly by using WAN to a VoIP phone in a different geographical location
If there are offices in New Delhi and Mumbai where each site has local PSTN gateway, calls originated from New Delhi IP phones must use the PSTN gateway installed within New Delhi office. Call must not route over WAN to use the PSTN gateway of remote office say Mumbai PSTN gateway.
Further to this, if PSTN gateway is located outside India, such calls are still not allowed. For example, if there are offices in India and San Jose, call made from India office must not use the PSTN gateway of San Jose as this connection results in revenue loss to service providers.
Other examples
1. Can we a have a conference bridge in India with users dialing from their IP phones or Lync Clients and at the same time some external parties (PSTN) joining that conference?
As regulation doesn't define the case explicitly, this scenario should be conditionally allowed. As long as conference bridge and IP phones are in the same geographical location and someone from PSTN joins the bridge, it's allowed. However, if conference bridge and IP phones joining conference are not in same geographical location, their calls should not get merged with PSTN users joining conference bridge.
2. If there are offices in New Delhi, Pune, Hyderabad and other global locations and conference bridge is in Delhi, can IP phones from Delhi, Pune and Hyderabad dial the conference bridge (on-net internal call) and at the same time have PSTN callers dial in from India/Global locations?
This scenario should not be allowed considering the fact that any IP call over WAN link should not get merged with PSTN.
3. Considering above case2, can all internal IP phones in India and global can have on-net conference through bridge located in Delhi?
This scenarios should be allowed considering regulations that call from VoIP phone to VoIP phone is allowed.
Notes:
1. Geographical location
Does geographical location limited to office, campus, city or state? Considering toll bypass perspective of service providers, geographical location should be limited to single site where service provider has given PSTN line.
For example, if we have two offices in the same city, this should be considered as two separate geographical locations.
University kind of installation which is widely spread and have multiple buildings should be considered as campus and come under single geographical location.
2. While deploying VoIP network within your enterprise, consult and cross verify with your service provider the legal call scenarios to avoid any regulatory issues.
3. Reference
Cisco documentation
Field discussions
