How we helped a Large Construction company save money by leveraging their current network infrastructure as a transport for voice calls between their multiple locations

How we helped a Large Construction company save money by leveraging their current network infrastructure as a transport for voice calls between their multiple locations

Business Challenge:

A large construction company with multiple locations around the United States seeks to implement a voip technology (Voice over IP) in order to save money and become more efficient.


  • Ensure that the user experience and call quality is the same as what it would have been if they were using the regular phone lines (PSTN).
  • The ability for the remote locations to call each other by the extensions and have the calls routed through the WAN network as opposed to going out through the phone company.
  • The requirement for an always-available phone system regardless of the WAN or the PSTN being down.
  • Save money by using the WAN to make phone calls
  • Utilize other benefits of an IP Telephony system, such as video, presence, extension mobility, etc

Our Solution:

VeeMost designed, planned and implemented the project in various stages. We implemented the headquarters IP Telephony network first before the remote locations. We leveraged Cisco ‘s Call Manager Solution, now known as Cisco Unified Communication Manager to accomplish all the objectives required of the phone system.

We deployed the following servers:

  • Cisco Publisher – handles data communication
  • Cisco Subscriber – to manage the calls
  • Cisco Unity – Voicemail
  • Cisco Presence Server (for presence)

These servers were set up to provide all the various features required by the organization. We installed Cisco IP Phones at all the remote locations. These phones would use the WAN to register with the headquarters Call Managers to receive their extension and call processing instructions.

In order to provide redundancy, we upgraded the remote routers to a CISCO ISR router that had the capability of SRST, which allows the router to take over and become a ‘mini-call manager’ in the event that the WAN or the Call Managers went down.

We also deployed a couple of POTS lines at those remote locations for emergency purposes and configured the system to use each remote sites POTS line for emergency calls such as 911. This was to avoid the scenario that usually occurs when the central call manager at the headquarter thinks that 911 calls are local to its location.

Some locations had a large number of users so we installed a call manager at those locations to support the number of users there since SRST limitations were exceeded there.

We configured the locations to use the WAN to dial each other, and use the PSTN to reach other when the WAN was down. This switchover happened automatically without the user knowing which route the phone call was taking. Users in one location calling a PSTN number that was cheaper from another location would route the calls through that location before it is transferred to the PSTN. For example, the users in Ohio calling a customer in California would have their calls automatically use the California Call Manager, where the calls to their California customer became a local call as opposed to the long distance call from Ohio.


  • Our customer started saving money by routing phone calls between locations over the WAN
  • We provided redundancy to the Headquarter Call Manager by installing another call manager in a second location, and also having the remote routers automatically use SRST and their local POTS lines to make phone calls when the call managers were down, ensuring that services were always available
  • Deploying QOS on the network ensured that the quality of the calls were identical to that of the PSTN
  • Users could dial between offices using extensions as opposed to using the full PSTN number.
  • During WAN failover, the users would still dial using extensions, and the local call processing agent would automatically route it out the secondary route and add the necessary numbers to get it through the PSTN.


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