Recently in Voice over IP Category

I've been waiting for this one for awhile, and thought it might come from someone like Skype...Skype has introduced the Open Sky - a service allowing you to directly link your VoIP system into Skype via a SIP trunk.

Soooo...if you're a true geek and run a VoIP home system (I use CCM or CCME), you can now directly link to Open Sky via SIP and not require a typical telephone provider to make outside calls.

The catch? You can only call Skype users...ehh...and only for a "short duration" depending on how busy things are.

So...almost there. Someday, we will have free PSTN calling through one of these types of service.

Here's the link with the information on OpenSky.

IP SLA has the ability to measure "real-time" WAN connection quality. You can then use the results of the measurement for routing decisions (such as choosing an alternate path). This is especially effective for VoIP connections. The following sample configuration can be used to create a IP SLA Jitter/Packet Loss monitor for use with VoIP deployments:

IP SLA Source

Source(config)#ip sla 100  !Some IOS versions use ip sla monitor
Source(config-ip-sla)#udp-jitter 172.16.1.2 65424 codec g729a
Source(config-ip-sla-jitter)#tos 176 !Marks packets with DSCP EF (IP Precedence 5)
Source(config-ip-sla-jitter)#exit
Source(config)#ip sla schedule 100 recurring start-time now
Source(config)#interface s0/1/0
Source(config-if)#ip address 172.16.1.1 255.255.255.0

IP SLA Responder

Responder(config)#ip sla responder !Some IOS versions use ip sla monitor
Responder(config)#interface s0/1
Responder(config-if)#ip address 172.16.1.2 255.255.255.0

My latest work has finally come to fruition: Cisco Press CCNA Voice. In approaching this book, I took a different strategy of writing. Rather than focusing solely on covering exam topics, it's written from a "let's build a VoIP network...step-by-step." It contains configuration example after configuration example, which is what I love when I'm looking for technical documentation. Check it out!

I've always been interested about VoIP security...it seems many networks running VoIP are now considering their security options (years after initial deployment). When I first looked through this book, I was unimpressed. It seems like the book spends A LOT of time talking through foundations of H.323, MGCP, SIP, encryption, authentication, etc... (just general security topics and voice concepts). However, Chapter 6 (Pages 128-173) makes the book worth the purchase. It walks through in "attack-counterattack" form ways that people can destroy your voice network and ways to mitigate these attacks. I really enjoyed the fact that the author shows you how to pull off the attack yourself in many of the sections so you can test to see if you've properly secured the network.

So...for the most part, the book could have been 50 pages long and I would have been happy with it. I guess that's about as much as I read from most books anyhow.

I've never seen a bigger VoIP migration than Cisco Systems. Just the thought of deploying 54,000 phones blows my mind...boy, if I could just charge that one on an hourly rate...

Anyhow, Cisco has just released a 132-page case study detailing...well...everything! How they did it, features they needed, pitfalls they fell into - it looks awesome. I haven't read through the whole thing, but plan on it. Good stuff!

Click here to get it.