You pick up your fixed line telephone and you can’t make a call – you’d be surprised? Probably yes. You turn to your computer, access to your corporate email is a bit slow and a site on the Internet doesn’t seem to be responding? Would you be surprised? Probably not. Our perceptions of the quality of service from each of these is often wildy different.
As part of your Unified Communications strategy, you may be talking to your service provider about migrating from traditional voice circuits, typically ISDN, to IP and SIP trunks – maybe even using ‘one fat IP pipe’ for all your network needs – corporate, Internet and voice – If you do this, can you still deliver the same user expectation for their voice service?
Voice over IP is nothing new. Many have been using it to carry internal voice traffic between corporate sites for many years. But to do this, they have typically done two things – compressed the voice to minimise the bandwidth used and deployed quality of service queuing mechanisms on their wide-area networks to ensure that time sensitive traffic such as voice gets priority. You should consider how these elements will interoperate with your service provider, if your UC solution is to provide a robust ‘dial-tone’.
Compression is great for conserving bandwidth but it does affect voice quality. For example, mobile phone calls are already compressed, if they are compressed again for transport over an IP network the quality may become unacceptible or even unintelligible! This can be critical in environments such as contact centres. Also, compression may stop other services working, such as fax. If you have an IP PBX or Microsoft Lync, check which compression types it supports.
If you are connected to your service provider by an MPLS-based network, quality of service for your voice traffice shouldn’t be an issue – but you may need to pay a premium for it. If you’re considering using an Internet-based service, remember that standard Internet access does not provide any quality of service guarantees. Again, it may be available, but you will have to pay extra and there may be technical limitations. Also, is your Internet service reliable and fast enough to support the required traffic?
Here's a quick check list of things to ask your provider:
• What compression if any is used? Ask for a demo and call from a mobile!
• How many calls are supported and how much bandwidth is needed?
• How will it integrate with your PBX?
• Does the service support fax and modems, if you still use them
• What happens when your connection fails? Can you have a backup connection/router?
• Can your telephone numbers be ported to the new service? What about access to Emergency Services?
• What quality of service mechanisms are supported?
• What SLAs, reporting and compensation is available if the service does not meet expectations?
Let me know of any success or horror stories you have!
Justin Ayres has 15 years' experience as a Unified Communications instructor, designer and implementer. He has 10 years' experience as a CCIE and specialist in Cisco's IPT and Unified Communications product set.