How to Configure Microsoft Lync to Use Cisco 3925 as a PSTN Gateway

We need to replace the current PSTN gateway device (extremely buggy, unreliable) with a certified gateway for Lync. The gateway device we use now has poor support and there is no on-site or after hours support.

When looking for a replacement, I see the Microsoft has certified our Cisco 3925E/K9 as a gateway for Lync. We have a killer Smartnet agreement with 24/7 support and 4 hour onsite, so this seems the perfect fit.

Presently the Cisco device sits outside of our Sonicwall firewall and simply acts as the connection to our Fiber internet link. So at present the only add-on is the SFP module for the fiber connection.

The question is this:

1 What all is required to make the 3925 Lync friendly? Mainly I know we need to at least add some sort of card for the PRI and FXS port. Are other modules recommended/suggested?

2 This Cisco device sits outside the firewall - whereas our current PSTN gateway device (and lync) are inside the network. Is it still possible do this config, or will it create a networking nightmare?

3 Lastly, since we still have a fax line (hence the need for the FXS port) - is it possible to have the Cisco device intercept calls to our fax DID's (we have 18) and route those to the FXS port? That way they don't pass to Lync, which wouldn't be supported.

I had also look at Dialogic as a solution, but given the mission critical nature of our voice service - the Cisco device seemed best. Are there any big tradeoffs going this route? I don't know Cisco IOS, however I do have a contractor who usually helps with config.

The best solution:

If you need PSTN GW for one E1 trunk and a couple of FXS' only, 39xx is a little to big for you.

But, of course, it will serve.

First that you need after recieving signal with PRI or FXS card is to encode the voice and to pack it to IP packets.

Cisco has a special module for this - PVDM. This module is equipped wis DSPs (Digital Signal Processors) to pack voice to IP. DSP calculator http://www.cisco.com/web/applicat/dsprecal/dsp_calc.html will help you to choose required PVDM module.

PSTN GW is not a gateway to public Internrt services, so you can place it inside your FW without any risk of intrusion.

And of course, it is possible to separate incoming in PRI trunk calls, for instance, by destination phone number, and directly translate all the calls with selected B-number to dedicated FXS port.

How to use a mini USB cable to Cisco 3750X switch console port

How to use a mini USB cable to Catalyst 3750 switch console port? what do I need to do to be able to console into the switch using the mini USB console port?

Here we will tell you what to do.

1 You can refer to http://www.cisco.com/en/US/docs/routers/access/1900/hardware/installation/guide/19cable.html#wp1057652 and try to configure the mini USB cable to Cisco 3750X switch console port.

Use the router for an example: Connecting the Console Cable to the Router. The principle is the same.

Step 1   Connect the end of the console cable with the RJ-45 connector to the light blue console port on the router, or USB 5-pin mini Type-B to the USB console port as shown in Figure. If connecting the USB port for the first time on a Windows based PC, you must install the Windows USB driver.

Step 2   Connect the end of the cable with the DB-9 connector (or USB Type-A) to the terminal or PC. If your terminal or PC has a console port that does not accommodate a DB-9 connector, you must provide an appropriate adapter for that port.

Step 3   To communicate with the router, start a terminal emulator application

Cisco 3750X Price visit www.3anetwork.com for the discount news.

Question about Stacking Cisco WS-C3750X-24S-S

Question: Existing Switch (stacked with another 3750G-24TS on same code) WS-C3750G-24TS: running 12.2(35)SE5 IP services (not universal image)

New Switch Cisco Catalyst 3750: WS-C3750X-24S-E : expect it will come with latest code, universal image.Are there any problems stacking 3750TS with 3750 XSeries. Whats the least disruptive way to do this?

Answer: The most important part is to match up the code level on the switches or they won't work together. I think it's more of a version match than the nitty gritty ipservices versus universal (with the IP services license).

show ver on a mixed stack:

Switch Ports Model              SW Version            SW Image                
------ ----- -----              ----------            ----------              
*    1 30    WS-C3750X-24       12.2(55)SE            C3750E-UNIVERSALK9-M    
     2 28    WS-C3750G-24TS-1U  12.2(55)SE            C3750-IPBASEK9-M        


One gotcha when mixing G with X series is the SDM template. The SDM template is a method used to distribute resources on the switches for use with different categories of processes. A quick Cisco search will get you the details, but it comes down to templates that are geared towards routing, switching, or a mixture (default) of the two. Each one opens up possibilities while also closing others. For example, the default allows you to run routing protocols, but only to a certain extent. If you were to configure a policy route, the command would not return an error, but also would not show up in the running config nor take effect. You would have to set the SDM template to routing for PBR to be truly configurable. Now for the gotcha... the SDM template names can be slightly different between G and X series - even just a capitol versus lower case letter. Whichever switch is the master as bootup determines the SDM template to push to all other stack members. Another thing is that the different switch types have different amounts of resources so the X series will be able to handle more in each template than the G series. I can't remember if all the switches went with the lowest common denominator, or if you're plainly running the risk of running out of resources on the G switches before the X switches.

The above gotcha may have been corrected in the new versions of code, but a couple years ago I went through this and had to settle with the default SDM template which limited some of the routing I was hoping to accomplish. If you're being affected by this, you will see the error at bootup.

Cisco 3750X  more information and the configuration, visit http://www.3anetwork.com/blog/ for more.