Unlike PSTN phones, you need to plug your modem, router or other VoIP hardware into the power supply for it to work. Clearly, this means that if there is a power failure, your phones go down. A UPS (Uninterruptible Power Supply) can help if you lose your primary power source as it will kick-in and keep your system running.
Shared connections
In a business context, it is likely that canada whatsapp number data you will be deploying VoIP over a broadband connection that is also used for other things such as server connectivity, email and downloads. This means that VoIP will only be allocated a share of your total bandwidth and may suffer at peak times, resulting in lower call quality.
It can be tricky to ensure adequate bandwidth is always available so it is a good idea to try not to use your internet connection for things other than VoIP when you are actually on a call. In addition, some businesses will opt for a dedicated line for VoIP so that there is no conflict. There are other priority and QoS (quality of service) mechanisms which can assist here.
Security risks
As with other internet-based systems and technologies, security is a significant concern when it comes to VoIP. The most relevant security issues concerning VoIP are viruses, malware, denial of service attacks, identity/service theft, phishing, and call tampering.