02. Could the IP Phone call to a PSTN phone or a mobile phone ? and vice versa?
Yes, the IP Phone can call to any PSTN or mobile number directly if you are joining the proper VoIP service provider (e.g. the Citron system). The provider could also give your IP Phone a number (like a PSTN number) that could be called by any PSTN phone or mobile phone.
03. Is it free to use the IP Phone to make a voice call ?
If this call is calling to another IP Phone, the call is basically free (suppose the Internet connection is already there). But if this call is calling to a PSTN number or a mobile number, then you need to pay to the VoIP service provider before (prepay) or after (post pay) the call.
04. What kind of network environment is needed for the IP Phone ?
The IP phone could basically work under any network environments including fixed IP (public IP and private IP) and dynamic IP (DHCP and PPPoE) network environments, even when there is only dial-up connection provided, Can use model EMT-747's built-in modem to dial to the network.
05. Is it possible to use the IP Phone behind a IP-Sharing device (NAT) ?
Yes, our IP Phone can work behind the IP-sharing device directly without doing any additional configuration on the IP-sharing device, you just plug in the IP Phone, and it will play. The NAT-passing-through technology works for both the ET-747H(H.323) and ET-747S(SIP) models if the proper VoIP service provider is selected.
06. How much network bandwidth is needed for each VoIP call ?
Approximately 15 kbps (kilo bits per second) is needed for one way of VoIP voice traffic. But when the silence compression function is enabled (default), the bandwidth is about half of that value( 7.5 kbps ) in average.
07. Is the IP Phone interoperable with Cisco VoIP devices ?
Yes, our IP Phone is interoperable with the Cisco VoIP devices including IP Phone model 7905, 7920, 7960 and gateway ATA-186 and AS-5300 series if they are running the SIP or H.323 firmware version.
08. Does the IP Phone support Power Over Ethernet ability ?
Yes, the Power over Ethernet function 802.3af is optional on the WAN port in all model.
09. What's a STUN server ?
A STUN (Simple Traversal of UDP Through NATs) server is a device in the Internet to help any VoIP device inside a NAT device to pass through that NAT device to call to other VoIP devices. But for most of the NAT devices in the market, this method is not successful.
10. What's an outbound proxy server ?
An outbound proxy server is another method to solve the NAT-passing-through problem, the technology is to use the outbound proxy server as the media(voice) relay, so, it can solve most of the NAT devices in the market. Our IP Phone devices support the standard outbound proxy server settings to solve this problem.
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