Here are some frequently asked questions about an Voice Over IP (VoIP).
Why choose VoIP?
What is Skype? Is this VoIP?
What do I need for a basic VoIP deployment?
What type of Internet connection do I need for a SIP trunk ?
Which VoIP provider should I use?
How good will the sound quality be?
Which IP phone should I get?
How difficult is it to get an IP phone working?
Does my computer need to be turned on to use VoIP?
Can I call any numbers using VoIP?
Can anyone call in to a VoIP phone?
Are their phones available to work with my Wireless Access Point?
When I travel, can I use my VoIP phone or soft client with me and use it?
How reliable is VoIP equipment?
Can I use my computer when I'm using an IP phone or a softphone?
Can I transfer my existing telephone number to my VoIP provider?
Can I dial emergency numbers with my VoIP phone?
Will my VoIP phone work when there is a power failure?
Can VoIP use Fax?
Voice over IP provides major benefits to both service providers and end users: Substantial cost reduction for service providers and enterprises, Increased revenues for service providers and Enhanced productivity for end users.
No, Skype is a free software programme that utilises a pier to pier Voice over IP application, meant for home use and not stable or secure enough for business. Skype is an application driven by a windows OS. Criticisms of Skype stands due to its "closed" architecture, and if you have a more powerful machine it may take over some of the machine's resources to become a "node" and support the calls of other Skype users. Skype does not use pure SIP and so is will not allow users to choose universal providers or equipment.
pbxnsip software, Internet connectivity and a broadband router or modem. You will also need a minimum single core PC, laptop or server and an IP phone. For multiple IP phones a power over Ethernet switch will be needed. Softphone are an option instead of an IP phone. You could also have the option of deploying a single or multiple hosted account from an ITSP for which you will be able to connect back to the ITSP server and utilise the functionality on their platform.
VoIP is dependent on connectivity so a broadband connection is vital. G711 codec will generally need at least 64 kbps download plus 64 kbps upload bandwidth to make a single uncompressed VoIP call.
If you use compression codec's such as G.723 or G.729 the bandwidth can be compressed to approximately 20 kbps per call. It is recommended that voice have dedicated connectivity and data be kept separate from the VoIP bandwidth in use.
VoIP is still relatively new in the market place and a stable platform is essential for business continuity, SIP providers can often be based on free software which can be unreliable if deployed incorrectly.
You need to consider bandwidth and speaker quality when looking at audio. You are better to invest in good quality IP handsets in order to take advantage of products on the market that offer HD Voice and that's use reliable components. Please see the Interop page for pbxnsip compatible handsets.
Please Interop page for pbxnsip compatible handsets.
pbxnsip configuration is quite straight forward, you will need account, password, registrar and outbound proxy. Configuring a handset can be found on the wiki: http://wiki.pbxnsip.com
Only when using a soft client. If the IP PBX is on a Server, this must be switched on.
VoIP is no different than traditional telecommunications. You can call any PSTN number or mobile number using an IP PBX or Hosted account. An IP PBX has the added benefit that SIP calls offer cheaper rates than PSTN minutes and that line rentals are much cheaper.
Yes. Given that the extension is active and registered correctly on the pbx and on the IP Handset then you will be able to accept calls from both other VoIP and PSTN users. VoIP also offer the benefit that you can purchase a traditionally geographic number such as an 0161 or 0113 and this can be registered/directed to any IP PBX, IP Address or Hosted account in any geographic location worldwide.
Wi-Fi technology is dependent on the strength of signal of the access point, however yes some mobile devices and IP Dect handsets support SIP, Symbian software on some Nokia mobile phones are SIP and GSM enabled as well as some blackberry and windows mobile devices having in built SIP client.
VoIP registrations whether a SIP client or IP Handset are dependent on connectivity, so providing that there are no firewall issues, you can plug and play on any internet connection with enough bandwidth.
There are many IP hardware manufacturers established in the market place and buying cheap equipment can often mean that budget components are used, it is advised to purchase quality kit in order to avoid disappointment and issues.
It is advisable to separate voice and data when deploying VoIP solutions however if mixed then CPU usage and bandwidth are affected by active programmes, email and internet use, data takes priority and can terminate an active call or cause one way or no audio.
This varies and is decided by the provider. Most SIP numbers cannot be ported away from the ITSP one registered.
Yes, however this depends on how you are terminating your calls.
Only if you have a generator backup for your network. VoIP equipment is dependent on electricity. Some gateway manufacturers allow for PSTN resilience and will take power from the legacy network.
Yes, pbxnsip is T.38 compliant however a fax to email or an ATA (analogue terminal adapter) is preferred by most users.
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