voip


Taking the plunge with SIP Trunks – Part 3

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Outbound calls; Matching a DDI/DID; Diagnosing problems; Internet bandwidth. Configuration for Outbound calling Part 2 looked only at the configuration for receiving inbound calls, but the SIP Trunk configuration form in Trixbox/FreePBX has to also include the settings for making outbound calls. It may not even work at all if you only use the inbound … Read more


Taking the plunge with SIP Trunks – Part 2

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Recap In part 1, I explained how a SIP Trunk is really just a virtual connection between your Asterisk PBX and the VoIP service provider. Standard SIP signalling is used on the trunk, but more than one simultaneous call is allowed and you may have more than one DDI number. Basic requirements to enable your … Read more


High Availability and Failover options for SIP and Asterisk

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Overview What’s the disaster we are trying to avoid? The assumed scenario is this: Some kind of centralised VoIP service is being offered to a number of users; the service operates on servers located at a data centre or office and the users each have a SIP client device, such as an IP phone, that … Read more


How do you choose the right VoIP Service Provider?

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VoIP Service Providers – the core services on offer Business and home users all have to choose from roughly the same pool of companies providing VoIP services, but the things that they are looking for may not completely overlap. Let’s consider a few of the more important services provided. Cheap calls Why use VoIP? Answer … Read more


What is NAT?

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What is NAT? NAT stands for Network Address Translation. Many devices sold as Firewalls or Routers are actually combined Firewall, Router and NAT device in one box. NAT is the mechanism that allows you to have many PC’s on your LAN all connected to the Internet through a single external IP address. When one of … Read more