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Lines and Calls

What is SIP / VoIP?


Session Initiation Protocol (SIP) it is the standard by which nearly all voice communications are made via an internet link.   SIP removes the need for traditional BT PSTN lines, or ISDN Channels – each of which typically costs £12-£14 per month.


The number of simultaneous calls can be made are determined by the amount of (SIP) Trunks your telephone system can take and how many you have purchased (and your internet speeds).   Although it sounds like you are swapping one cost for a slightly lower one there are other benefits you should be aware of:-



How does it help me?


The primary benefit is lower call costs; calls from remote workers using IP Phones into the office are free and they are ‘seen’ by the telephone system as being part of the network so that they are included in any ring or Hunt Groups and other dialling rules exactly the same as any other telephone extension.   Other calls, local, national, mobile and often international are typically lower than when using traditional BT lines.  


Beyond call cost savings, by using SIP businesses are no longer tied to their local telephone exchange meaning that they can move premises and keep the same number and gain telephone numbers that are from different locations, not only the nearest city but another country.  


As importantly a SIP enabled telephone system gives you flexibility, as your business expands or contracts simply add or remove SIP trunks.  



What else should I know?


One major item to be aware of with SIP is the number of simultaneous calls, as mentioned before is your internet speed.   An easy way to calculate if your internet line can handle the number of calls you want is for every 10 simultaneous calls you will need 1Mbps upload speed.  Upload speed is vital, 100k each user makes the maths easy and will give a high quality audio, you can use lower than 100k however anything below 80k users will notice the difference in audio quality.  In order to check how fast your speed is there are many websites you can use, one of the best is, remember to click on “begin test” and then look for Upload which is measured in Mbps (each 1Mbps = 10 x 100k).


What should I do now?


Many telephone systems can be upgraded to use SIP or a Gateway can be added, the costs to do so are quickly recovered depending on the number of calls you make and how many PSTN or ISDN lines you can stop paying for.


To find out if your phone system can be upgraded and if you can get suitable internet then call 01793 822133 or email