New features! Video Based Screen Sharing (VBSS) in meetings, enables much more efficient screen sharing with fluid motion (not the 2fps we’re used to in meetings. Multiple Emergency Numbers in a location policy, useful for universities that may have their own local emergency number in addition to 911 Busy Options like Busy on Busy and Voicemail on Busy. Get it here: https://support.microsoft.com/en-us/kb/3061064
Ever wondered what a proper T.38 Fax over IP (FoIP) transmission looks like running through Wireshark? Maybe you’re troubleshooting a call flow, or never seen a T.38 capture. Below I’ll try to explain the call flow and steps to look out for when troubleshooting T.38 calls. Here’s an Outbound FAX call originating from a FXS port in a Cisco CUBE, and going towards Flowroute. Initial SIP INVITE and early media receipt (ringback). Note this is all RTP. SDP from the INVITE shows media offered is all voice (RTP) 183 Session in Progress, and we start sending media too (again, RTP). Later on comes the 200 OK, meaning the call was answered on the remote end. Things changing now… in-dialog (RE)INVITE from Cisco CUBE to SIP trunk… RTP and T.38 packets mixed because the remote end has not accepted our INVITE yet, but we start sending media either way. And the SDP of the new INVITE now shows all T.38 media now. Once we get the 200 OK from Flowroute, it’s all T.38 media both ways. Now the flow gets interesting, more Fax-ey. Wireshark will decode the HDLC data and show interesting bits here TSI, is our Fax station number programmed in the machine. DCS, our Fax machine communicates the capabilities, and starts training. If we look inside the packet’s data, our DCS has a lot more information about our Fax machine’s settings and resolution Then we get an FTT, means the remote end “Failed to Train”. Not usually a sign something is wrong, but more a capability mismatch. The remote fax may accept only lower baud rates, and will fail to train any higher. This is normal unless it’s the only response we get back from the remote end. We see the same process of TSI, DCS and FTT until we hit the right baud rate… in our case it’s 9600… Once we get that, we receive a CFR. Followed by a short training to sync-up and data (because we did long training before the CFR) And our actual FAX data which will vary At the end of the data, Wireshark reassembles the packets and tells us whether there was a loss or not. In our case, we’re good! We send an EOP to signal the end of the transmission The remote end does an MCF to acknowledge receipt (this is how your Fax machine knows the fax is “good” on the other end) And then we send a DCN to logically hang up the HDLC stream, but we wait for the remote end… Remote end hangs up the call… and we’re done… And that was it. Many exchanges and training but in the end our page was sent over a SIP trunk, negotiating T.38, training with the remote fax machine at 9600 baud, and transmitting one page in about a minute.
Sophos UTM v9 comes with the tcpdump utility, which lets you run packet captures from the shell. This is great and all, but in order to look at those pcaps with Wireshark, you need to pipe to a file, copy the file, then run Wireshark against it. Annoying. All of it. What if we could remotely capture packets over an SSH tunnel? YES… turns out it’s a bit tricky if you’re on Windows, and the authentication piece to get root access without having to do the loginuser first. How? Keep reading… ...
VMware’s Performance Best Practices mentions you should set power management in the BIOS to “OS Controlled Mode” or equivalent. This is so you can control power saving from the hypervisor itself. It’s very useful when you want to change these settings on the fly without having to reboot into the BIOS, similar to how Windows power profiles work. But the “gotcha” here, which is also mentioned in the best practices documentation, is that the default Power Policy setting is set to Balanced, when you most likely want to set this to High Performance, as you’ll see later… ...
So… VMware’s NSX is super awesome! I’m one of those weird guys that find playing with networking and virtualization on a Monday night more fun and exciting than a weekend in Vegas. Ok, maybe not so much, but still somehow I managed to stay up past midnight deploying an NSX “Lab” just by messing with it. I say screw the guide, I learn better by just pressing buttons and breaking things… I’m not doing this for a client so what gives? Let’s poke… ...
Released last week, new technical diagrams in Visio and PDF for Skype for Business workloads, Call Quality Methodology (CQM) and different hybrid scenarios. https://technet.microsoft.com/en-us/library/dn594589.aspx
My first attempt at a semi-useful PowerShell script. This script will export all UM prompts from all dial plans and auto attendants for Exchange 2010 and 2013. The output of the script is a collection of files with WAV extension on the running directory, matching the names of the custom prompts. Future changes: Set a working folder, and organize the prompts into folders based on AA and DP name. The output files are in WAV extension, but are actually MP3 files (Insert blame for Export-UMPrompt). There is another script coming that will convert these files from MP3 to 8Khz Mono PCM WAV files so they can be reused for other UM attendants. ...
Skype for Business for Android is out of preview and finally released. Time to try it with the Grandstream GXV3275… https://blogs.office.com/2015/12/16/skype-for-business-for-android-now-available/?wt.mc_id=soc_li_Office-365_Skype-for-Business_null&ls=soc&ca=Office-365&lsd=li&Ocid=1%20-%20Fans_Social_LINKEDIN_COMPANY_Skype%20for%20Business_20151216_305715181
Released 11/17 and fixes an issue with Windows 10 users over Edge not able to join meetings using the Skype Web App. It also adds a new Shared Line Appearance (SLA). More details on that here: https://support.microsoft.com/en-us/kb/3092727 Get the CU here: https://www.microsoft.com/en-us/download/details.aspx?id=47690
Paul Bloem’s stencils blow anything else out of the water. Zeacom servers, AudioCodes SBC’s, and better looking Skype for Business roles, even the CQD! What else could I want? Excellent job Paul. I’ve shared this with my colleagues so they better vote 5 stars! https://gallery.technet.microsoft.com/office/Skype-for-Business-2015-4a8f03dc