Interconnecting with SIP.US - The Basics

This is a set of basic networking requirements and terminologies for connecting to SIP.US

Gateways

The most efficient way to ensure redundancy is to use DNS SRV. If your PBX supports DNS SRV, pointing to gw.sip.us as your proxy IP address is all that should be necessary to ensure redundancy.

If your PBX does not support DNS SRV, hopefully it supports configuration of multiple outbound proxies. If the system supports a primary and backup SIP proxy, use gw1.sip.us for the primary SIP proxy, and gw2.sip.us for the backup SIP proxy. (You must use both gw1.sip.us and gw2.sip.us to be fully redundant.)

Our gateways will only accept SIP traffic on UDP port 5060.

Audio

Audio related to SIP calls is delivered via RTP over UDP. Since our SIP gateways are just a proxy, the audio can be delivered from various IP addresses and many different ports. 

NAT

NAT stands for Network Address Translation. Most customers are behind some form of NAT, and many do not have a static IP address. Try to connect your PBX or softphone through our service without any special NAT configuration. If it becomes apparent that you may be having a NAT issue, there are three possible solutions:

ALG: If your router or firewall is capable of properly implementing ALG, enabling it may alleviate your issue

STATIC IP:  Your internet service provider (ISP) may provide a static IP at an additional cost

Security

Network security can be a consideration when implementing a VoIP solution. Here are some basic tips:

1. You should allow incoming SIP traffic from:

• Individual IPs 65.254.44.194 and 74.81.71.18 and Subnets 104.219.162.0/24 and 104.219.163.0/24 
• If you cannot allow subnets then please allow individual IPs 104.219.162.40, 104.219.163.117, 65.254.44.194 and 74.81.71.18

2. You should forward all RTP ports used by your device to the private IP address of your device if it is behind NAT

3. Your SIP device should only accept RTP traffic for a SIP call which is active, so the forwarding in tip 2, above, should not be accompanied with blocking traffic from certain IP addresses (see here for an extended explanation).

4. If your device is accessible from the internet, choose a strong password, or preferably, consider disallowing anyone from logging in through the internet