Transition from the PSTN to VoIP

Not if but When

It is not a question of if, but when. As the number of switched PSTN lines drop each year and even major carriers are switching their operations to VoIP. For example in the US, a recent survey showed that almost a quarter of household surveyed no longer had a fixed landline as consumers are turning to their mobile phone as the primary source of connectivity. This has been encouraged at times even by the operators who are packaging VoIP alongside their high-speed internet services. Indeed, for telephone service operators are even transitioning to VoIP with PSTN switches being replaced with VoIP over LTE (4G) mobile networks. The reason for this is simply costs; it costs 10 times as much to power and cool a switch room of TDM switches as it does a VoIP data center. In addition, PSTN switches take up to 10 times more floor space.

So if the major telecom companies are switching over from the PSTN to VoIP because of costs why are enterprises and small medium businesses?


The Reasons to Switch

The reasons that business is making the transition in increasingly large numbers each year is also due to cost savings. However, there are other reasons such as their existing PSTN PBX is just no longer competitive with regards functions and features. Where once the PBX ruled in providing business class features this is no longer the case as cloud based IP PBX have become cheaper and more capable. Today’s IP PBX hosted by a cloud provider will offer all and a lot more of the features of even the top of the range traditional PBX and at a fraction of the cost.


Changing Times

However, not just raw economics is at play, but a changing landscape as people are communicating differently as new channels have arisen over the last few decades. Prior to the advent of the internet, the telephone was the standard means of communication for business along with the postal service. Email ha a major effect on call rates as people especially business-to-business communication shifted toward first point of contact being through email rather than a letter or a phone call. Similarly, social media, SMS and IM have started to take a similar toll on email as people find better or more convenient methods to communicate. The humble telephone call has dropped down the list and is now used more for formal communications were once face-to-face meetings would have been the norm. Of course, video conferencing and video calls are commonplace now and have become almost a de facto standard for remote meetings, presentations and interviews.

However, if the transition from the PSTN to VoIP is almost inevitable over the next decade how do we go about it, I mean how do you replace the PBX in the business with either an on-premises PBX or a cloud based VoIP system?


Migration Path

If the reasons for migrating are clear, why are more companies not doing it? Well the reason for that is it is not that simple and most of the pain comes in the transition costs. Therefore, what you will save will be in future money, to transition from the PSTN to VoIP will cost you today’s money, that stuff you have in the bank. However, despite what we have said previously, or perhaps in support of it, I.E the telephone being now a more formal means of communication, companies are loathe to suffer any downtime as it could cost them important business. Therefore, any migration plan must cater for a zero or at the least minimal downtime plan. If that is the case then how should we proceed with a minimal downtime migration plan?

  1. Ensure your current PBX supports SIP termination – If it does then you’re in luck as all you really need to do is contact your existing Telecom provider to provide you with their SIP service or failing that contact another SIP provider directly. If you’re existing, PBX doesn’t support SIP you will need to go out and buy a SIP gateway. This is just an IP voice to PSTN convertor; alternatively, you could just buy a VoIP PBX.
  2. Moving the existing lines and numbers – when migrating you are most likely wanting to move existing business numbers and all your extension plans over to the new IP system. This is called local number portability and you will need to supply all the real phone numbers to the new SIP provider to manage the handover. This is why it is best to try going through your existing telecom provider first. For your internal extension plans, these don’t require portability but you should have the extension plan documented so that you can use this to configure the new IP service.
  3. Don’t rush in – move a single business line, preferable a test number with a few extensions first. This will enable you to test the migration process before committing your important sites to the migration.
  4. Install in parallel if possible – if you are migrating to a P PBX then install the system in parallel to the existing PBX. This way both systems will work until users are comfortable with the new system an you can move over gracefully. One drawback to this approach is that some users may resist the change an you may have to keep running both systems indefinitely, so make a deadline for the old system and once training and familiarization is completed switch off the old PBX


VoIP Infrastructure

What we are missing from the migration plan above is the transition from the existing telephone structure to an IP cable infrastructure. Standard telephone cabling may look the same as Ethernet IP cabling but it isn’t they are graded differently. Telephone cable is Cat ¾ while IP cabling for higher bandwidths and longer distances requires Cat 5/6 so don’t try to reuse the existing telephone cabling to the desks. There are two alternatives here use the existing data network cabling if there is any to the desktops to share the cable for data and voice or run a spate infrastructure purely for voice. The latter is infinitely better though it is more expensive it is far superior and will save you from a lot of problems and user-induced headaches in the future regard their perception of call quality and hard to trace reasons for dropped calls.


Testing the Cabling

The main problems with call quality with VoIP internally, extension to extension is down to poor cabling and lack of bandwidth, see above. Quality issues should not arise internally as there should be loads of bandwidth however, you should still configure QoS to give voice packets priority over data should any congestion arise. Testing the cable is relatively easy all you need to look for are two parameters jitter and latency, and both can be tested easily. However first let’s look to see what latency is, how do we measure it, and what are the acceptable limits.

With latency, which is the delay induced by the network as packets travel from one phone to the other. IP LANs will introduce minimal delay an should never be an issue, the Internet on the other hand will introduce varying levels of inconsistent delay an being unpredictable it is difficult to cater for. The simplest tool for measuring delay is Ping, set a continuous Ping (echo request) going between the telephone en-points an note the time taken to reply. VoIP requires less than 130 ms one way latency, remember though that your Ping times are two way, so you are looking for roughly anything under 260 ms on the Ping times, anything above that will introduce speech delay. However, latency is not that bad in reality think for example of a telephone call over a satellite link, the sound quality is normally fine it is the delay between the transition of conversation between parties and that awful silence that is the problem. However, if both parties are aware of this and expect that standard delay there is not a problem. Here delay really is an issue is when it is variable, and this is termed jitter. It is the variation between the times of the Ping echo replies. A VoIP call can work fine with jitter less that 30ms after that other concerns will be introduced like lost packets and out of order packets, which affect voice quality.


Moving to the Cloud

A good option if you want an easy life is to move the telephone service into the cloud n order to take advantage of the provider’s expertise and capital outlay. Simply you will benefit by economy of scale, by sharing the IP PBX system with many others in a multi-tenant clouds configuration, this relates to huge cost savings. Furthermore you will be using a top of the range fully features IP PBX which normally might have been out with you budget if you were to buy it and operate it yourself.

  • Inspect your Network before deploying to the cloud – Successfully migrating to a cloud service provider requires that you adequately prepare your network for the bandwidth, latency and jitter, requirements, as well as voice prioritization through QoS.
  • Compare the performance between SIP trunking and hosted VoIP – an SIP trunk is the preferable solution but it will be an extra expense however it should be considered to be well worth the cost. A SIP link is in effect a VoIP equivalent of a private line that can connect your premises over the internet to the service provider. which facilitates an increase in voice quality and reliability. The cheaper alternative is to use a standard internet connection but that exposes you to all the potential problems of the internet with regards lack of bandwidth, latency and packet loss.
  • Cloud features are great for business – the big advantage with a cloud service is the multitude of features and functions that come with it, such as video calling, call recording, auto attendant and mobile phone integration. These are certainly available in hosted IP PBX but can be difficult to set up, configure and maintain to a high standard.


Securing VoIP

With the PSTN, you have become spoilt by the transparent security that is inherent to the telephone network. Despite what is shown on TV it is very difficult to tap telephone lines without direct access to either the exchange or the handset itself. With IP that all changes, VoIP is as easy or difficult to hack as any other data packet crossing the internet so you need to take precautions.

The first step is inside the company and counter VoIP security risks by using a separate physical cabling plan dedicated to voice only and then use a voice VLAN overlay one VLAN per extension.

However to ensure adequate VoIP security follow this five point plan.

Five Steps to VoIP Security

  1. Make sure you network infrastructure, firewalls, VPN’s etc are voice optimized and capable of supporting advanced security requirements for VOIP.
  2. Ensure your firewalls and security controls are up to date with the latest security vulnerabilities fixes downloaded. This is extremely important for on-premises PBX’s hosted on a windows server.
  3. Properly secure any remote access points such as VPNs and eliminate any potential backdoors into the network
  4. If the voice calls are confidential and traversing, the internet, perhaps even the WAN, considers using encryption. However don’t forget the LAN, if calls are sensitive use encryption for all calls, don’t assume that the internal network is safe, it rarely is, employees are forever downloading and messing about with free hacking tools.
  5. Structure you network and use dedicated VLANS per extension an ensure access to any switches is strictly controlled this will prevent an intruder spanning ports to eavesdrop or reconfiguring VLANS.


Bottom Line

When migrating from the PSTN telephone system to VoIP there are several steps you must follow, these are:

  1. Establish a migration Plan.
  2. Structure your network and introduce VLANS per extension,
  3. Consider the Cloud – you will get more for your money and less headaches with maintenance and support
  4. Security – If possible, use encryption on all calls an if the VoIP solution is on-premises secure the server, make sure it has the latest security patches and don’t allow any unauthorized persons near the Ethernet switches.

Run both the PSTN and VoIP systems in parallel till you and the users are happy and confident using the VOIP system, however don’t delay switching over for too long, or it might never happen.

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