Voice over Internet Protocol (VoIP) enables enterprises to use the Internet as transmission medium for telephone calls by sending voice data in packets using IP rather than by traditional circuit transmissions of the PSTN.
In short, it’s a way to carry phone calls (audio) over an IP data network (internal or external). Turning analog phone signals into digital signals provides flexibility to embed audio video payloads into business processes.
VoIP helps enterprises to save cost on communication . Long-distance phone calls become inexpensive after moving away from public switched telephone networks (PSTN). This is because the calls are no more processed over commercial telecommunications line (costlier), instead,calls are processed over company owner or external internet network (cheaper).
VoIP system allows an enterprise to define least cost call routing in more flexible and smarter ways. The least-cost call routing chooses which path, on the data network, the call should take, and then at what egress point the call should join the PSTN, selecting the cheapest carrier, so that the user pays the lowest possible cost.
Similarly, it also choses the ingress point for PSTN service provider to route the call to internal network . Thus, paying for the least distance and using the internal\external IP based network extensively.
It works quite well in most of the countries where VoIP regulations are not so strict. However, there are many countries with a bit of tight bureaucracy in this regard. Such countries have stringent telecom restrictions. These restrictions require national or international long distance calls to go over PSTN, instead of utilizing the advanced least-cost routing system. Primary drivers for such restrictions are to;
- Preserve national and international tolls
- National Security/Legal Intercept
These regulations exist in over 50 countries, including India, China, Brazil, Algeria, Bahrain, UAE, etc.
Reference Diagram – A use case where inter-site call routing on IP network is not allowed.
In deploying VoIP in such countries, enterprises need to adhere to regulatory requirements. Basically the architecture and design should consider following facts carefully.
Forcing select calls to be routed over the PSTN in a compliant manner. Identify the types of peer to peer & conferencing calls which may result into toll bypass. Block them if not complaint per local law.
Design country specific routes (and dial plans) to ensure there is no non-compliance. Enterprises having presence in multiple countries need to define dial plan and routes in more informed manner.
Design voice and data network convergence as per the local law. Telephony restrictions in such countries vary tremendously. Somewhere it could be to avoid toll bypass completely, and somewhere it could be partially.
Use IP network to route all voice traffic between the corporate sites. This would reduce the inter site calling costs. This might be an interesting design as it may require the users to have two lines (numbers) on the desk.
Type of actions could be Allow, Allow with routing restrictions, or Block the call or conference call escalation. The action could be applied to both inbound and outbound calls at the call signalling (SIP INVITE) level. Also, the action should be applied to all forked call legs for inbound calls.
Study and implement compliance for users who are roaming at different enterprise locations, both nationally and internationally.
Logical Partitioning Partitioning in communication system enables enterprises to control calls basis of specific allowed or forbidden configurations.
Basically,it allows configuration of Unified Communications (UC) systems in a way to prevent restricted calls calls that mix VoIP and PSTN resources when calls occur between different geolocations. You need to have proper understanding of calls that are allowed and calls that are not allowed per geo location. Logical partitioning then would help you configure the call routing accordingly.
Logical partitioning are supported in different ways ways by various Unified Communications (UC) vendors. Some vendors require the deployment of two parallel PBX systems with two separate phones for each user. While others may support single communication server setup without requiring two separate devices\applications.
Also, some vendors do support logical partitioning for roaming users while others don’t.
As an architect, we wish to have a world without or with less telephony restrictions. Until then, happy designing a legally compliant voice architecture!!!