Why calls break up on a connection that tests clean, and how to prove where the fault is.
It is being written. The outline below is what it will cover, and it is unlikely to change much. There is no enrolment and no date — when it is ready it will be on this page. Several of the lessons are built around tools on this site that already work, so you can practise the measurements today.
If you need this capability now rather than later, UCaaS & voice is the service that covers it, or talk to us.
Anyone who has been told the phone system is broken and suspects the network, or the other way round.
Practitioner. For people who administer these systems day to day.
Assumed beforehand:
3 modules, 10 lessons, 1 h 49 m of material. The times are the sum of the lessons rather than a round figure.
Four impairments, each with a different cause and a different fix.
Why variation matters more than delay, and what a jitter buffer costs.
One percent, bursts against random loss, and what the codec can paper over.
Bufferbloat: the connection that tests fine until somebody uploads something.
Where the budget goes, including the parts you control.
The codec rate is the audio. The circuit carries considerably more than that.
RTP, UDP, IP and framing, and why a compressed codec saves less than its bitrate.
The interval, the packet rate, and the delay each choice adds.
Concurrency, headroom, and why a full link queues.
Signalling and media take different paths, and NAT understands neither.
Address rewriting, symmetric RTP, STUN and TURN.
What it tries to do, and why it is the first thing to disable.
The E-model, its inputs, and what an estimate is not.
Format. Written lessons paired with this site’s VoIP test, bufferbloat test and bandwidth calculator, so each measurement is one you have taken yourself. Delivery mechanism is not built yet.
These tools run the same checks the course teaches, and they work today. No account, and the ones marked as running in your browser send nothing anywhere.
Addressing, DNS, DHCP and NAT — and a method for finding which of them is broken.
Course outline ⟶Chains, names, renewal and the expiry that takes a service down on a Sunday.
Course outline ⟶The attacks that pass SPF, DKIM and DMARC, and the habits that catch them anyway.
Course outline ⟶This course exists because the work behind it is work we do. If you need the result rather than the skill, ucaas & voice is the service that covers it.