Below are some frequent questions we are asked about SIP/VoIP


I have one-way audio – IP routing issue, check firewall settings and ports.

SIP telephone will not register/provision – IP routing issue, can you ping the provisioning server?

Call quality or lost audio problems – Traffic issues, your ISP may be busy or having issues

Buzzing on the line – Caused by analogue devices, faulty cable/adapter or ATA.

Echo during calls – Reconnect call, if problem continues possible traffic issues (see above).


Here are some basic firewall configuration settings for SIP/VoIP


Most SIP/VoIP telephony providers have specific ports and settings that may need altering on your firewall.

The following are common firewall ports and settings that are needed for most SIP/VoIP communications providers:

TCP – 80

TCP – 443

UDP – 10000 to 60000

UDP – 53

UDP – 123

TCP & UDP – 5060 & 5062


SIP ALG Disabled

SPI Disabled


Always check with your SIP provider to confirm the correct firewall configuration required for your SIP/VoIP telephone.

Most good hosted telephony providers also offer further support for configuring and provisioning your SIP/VoIP telephone on their hosted telephony service. Read More…


Currently available SIP telephones from our online shop: