Home Lab (Voice Interfaces and Modules)

Let’s delve into the myriad of options that are available to terminate your voice channels in your home lab. While there are a lot of options, the voice interfaces can be summarized as being first generation and second generation. First generation voice interfaces will cost far less than second generation voice interfaces, but most of them are not officially supported for the 2811 ISR gateway router I suggested in the last blog. There are some first generation hardware options that you only want to consider if you’re on a tight budget and you have decided to use the 2600 XM series routers. The first generation hardware includes the following network modules (NM) and voice interface cards (VICs): • NM-1V (1 VIC slot) • NM-2V (2 VIC slots) • NM-HDV • VIC-2FXO • VIC-2FXS The first generation FXO modules have some limitations that you should be aware of if you plan on turning your home into an IP Telephony network like I did. I connected my router’s FXO port to the copper telephony wiring in my home by plugging the RJ-11 interface into a wall jack. The router’s FXO port then picked up inbound calls to my house after one ring. I configured the MGCP and/or H.323 gateway to dial a phone number that was shared between the analog phone plugged into my FXS port and two IP phones. Unfortunately, I lost Caller-ID, Call Waiting, and Call Waiting with Caller-ID functionality. All mentioned features require battery reversal and the first generation FXO card did not have it. Cisco’s VIC-2FXO M1 card would have provided these features, but the year was 2002 and I had run out of discretionary income. Missy and I decided that VoIP was cool, but we didn’t want to lose our features. Fortunately, the first generation T1 and E1 voice/WAN interface card (VWIC) are supported on the 2800 router because the second generation VWICs (VWIC2) are expensive. For VIC, WIC, and VWIC compatibility information, check out http://tinyurl/2800list. When I first put together my lab, I didn’t have the budget for two routers, two NM-HDV modules with a VWIC-1MFT-T1 for each. If you are on a budget, buy one router with FXS and FXO VICs. You can buy another gateway and T1 interfaces later. If you decide to purchase a 2811 router, you will not need an NM-HDV or NM-HDV2 (2nd generation) to house the VWIC card. The VWIC card can go into one of the four built-in HVWIC slots (High-density Voice WAN Interface Card). We will continue our coverage of voice hardware in the next blog. The focus will be on second generation NMs and VICs.