In the first two issues of Fusion, we explained the differences between Internet and carrier IP trunk services, detailing how the former worked and its suitability. In this article, Falk Bleyl, Senior VoIP Product Manager at THUS, focuses on carrier IP trunk services using THUS IP Exchange Lines as an example. He explains what type of businesses should be considering this service and the potential benefits they could realise.
IP Exchange Lines
IP Exchange Lines are suitable for organisations that currently have an ISDN telephony service in place and where consistent quality, performance and security are key requirements. The THUS IP Exchange Line service is an evolution from ISDN telephony services (mainly ISDN30), which is the current standard for larger PBX connectivity. Instead of being delivered over ISDN30 from a traditional telephone exchange, IP Exchange Lines are provided from THUS' softswitch across THUS' Next-Generation Network and presented as an IP connection.
IP Exchange Lines allow customers to either replace or complement traditional circuit-switched voice services with next-generation packet-switched telephony as part of a PBX migration to IP. In many instances, customers will retain some ISDN connectivity for local break-out or backup or replace ISDN services as part of a migration plan over time.
Requirements
IP Exchange Lines provide access to the PSTN and businesses will need to subscribe to one of three data services provided across THUS' Next-Generation Network in order to use the service:
- MPLS IP VPN
- National Ethernet
- High Speed Internet over Ethernet
To take advantage of the service customers will also require an H.323 (version 4) compliant IP PBX or IP-enabled PBX that has IP trunk capability. The choice of end-user interface is the customer's and may consist of analogue handsets, IP handsets or softclients.
When considered at the design stage, IP Exchange Lines can reduce or even eliminate the capital expenditure for IP-PSTN gateways and provide greater flexibility and control.
As a direct consequence of using the underlying data network for converged connectivity, IP Exchange Lines benefit from the nationwide reach of THUS' Next-Generation Network, as well as the access and resilience options, availability and performance associated with the respective data services. IP Exchange Lines are not provided across the public Internet.
Benefits
Businesses that currently use ISDN30 as a basis for their telephony system are now considering moving to a VoIP service such as IP Exchange Lines. There are a number of factors driving this trend, including the fact that ISDN lines are more expensive than IP-based telephony equivalents. In addition, with IP Exchange Lines, one of the key benefits is potential location independence for the various devices that make up an IP telephony system by interacting more closely with a customer's IP PBX.
Rather than having to deploy a PBX (or for IP telephony an IP-PSTN gateway) at each location where services and telephone numbers are required, IP Exchange Lines can centralise and consolidate PSTN access, reducing or even eliminating the cost for PSTN break-out at certain sites. Less hardware is generally required to connect to IP trunks (a single Ethernet connection on an IP PBX can deliver multiple ISDN30 equivalent services), leading to reduced CAPEX and OPEX.
IP Exchange Lines do not traverse the public Internet, making the service fundamentally different from trunk or exchange line services provided by Internet Telephony Service Providers (ITSPs). Exchange Lines are also able to offer the required security, performance and voice quality demanded by businesses. Internet-based services can be unsuitable for businesses as they have inherent drawbacks as a result of the transport network across which they traverse (the main ones being performance and security issues). They also cross networks that are unknown and/or invisible to the user, which may be a key factor for performance issues. IP Exchange Lines, on the other hand, bring together the security and performance advantages of ISDN with the flexibility and future proofing of IP, as illustrated below.
IP Exchange Lines in practice
To illustrate how IP Exchange Lines can benefit organisations, here are some real-life examples:
- A value-added reseller procured a THUS MPLS IP VPN network to offer an end-to-end communication service to an end customer. Part of the service was an IP Telephony deployment, which used THUS IP Exchange Lines as exclusive connectivity to the PSTN. Geographic numbers were provided to offer local number presence in more than one location. This enables end users to call a local number in one city, while the calls are actually delivered and answered in another location. IP Exchange Lines made this much easier and cost effective than it would have been possible using traditional ISDN circuits, drawing on the benefits outlined above. Many changes can also be configured remotely without having to send an engineer to the site.
- A manufacturing business has been using THUS' National Ethernet services for several years. As part of a technology refresh and network restructuring, IP Telephony was recently deployed and IP Exchange Lines were considered at the design stage. This removed the need for a separate ISDN30 at a new site, including the IP-PSTN hardware that would have otherwise been required. The service deployment happened in half the time it would have taken for an ISDN circuit and the install and rental costs were lower too.
In summary
There are a number of benefits arising from the deployment of IP Exchange Lines. Not all of them are linked to direct service costs either; they extend to less hardware being required, faster deployment speeds, as well as greater scalability and flexibility than is offered by ISDN. Coupled with inherent performance guarantees and security due to the fact that IP Exchange Lines are not delivered across the Internet, customers truly get the best of both the 'old' and 'new' worlds.