At some point you may decide to integrate various H.323 endpoints, such as any PC running Microsoft's NetMeeting, or some of the free VoIP clients mentioned in previous tips, like Open Phone, into your IP Telephony environment, so that you can make calls to your IP Phones. So in that vein, this tip discusses the basic steps for connecting
First, set up a gatekeeper. Try downloading one of the free gatekeepers if you don't have one already. If your Cisco router is running a version of IOS that includes gatekeeper software, you could configure it like so:
! gatekeeper zone local <yourzonename> <yourdomainname> gw-type-prefix <string> default-technology gw ipaddr <CallManager's IP address> no shutdown !
Next, configure your call manager to register with the gatekeeper. Do this by choosing Gatekeeper from the Device menu. Next put the gatekeepers IP address (or name if it's in DNS) in the "Gatekeeper Name" field. Change your terminal type to "Gatekway". Select a device pool and type in the zone name. Then, check the "Allow Anonymous Calls" box and set the Device Protocol to H.225.
Finally, you need to configure your NetMeeting clients. Choose "Options" from the "Tools" menu. Type in a name in the First Name box then hit "Advanced Calling". Check the box that says "Use a gatekeeper" and enter the IP address of your gatekeeper (not your CallManager). Next, check the box that says "Log on using my phone number" and enter an extension. Click Ok twice and you're done!
Both your CallManager and NetMeeting should be registered with your gatekeeper and you should be allowed to place calls now. Of course, if you're doing this for a production environment, there's a lot more you want to take into consideration and test before you deploy. The following are some gotchas to keep in mind:
- NetMeeting and IP Phones and gateways don't always negotiate codecs well. Consider carefully what region you place NetMeeting devices in.
- CallManager can only register with a single gatekeeper and the configuration isn't terribly flexible. Make sure the "Terminal type" and "Device Protocol" settings don't trample on other functions.
- Think about how you're going to keep track of NetMeeting phone numbers. Since they're just a text field, count on users messing with them. Conflicts are a given.
- If you have a more sophisticated environment with directory services, you can take advantage of other types of login, but be careful, as CallManager will want to register with the gatekeeper using it's H323-id and this can cause you grief on the gatekeeper if your NetMeeting clients are logging in with their phone numbers.
Thomas Alexander Lancaster IV is a consultant and author with over ten years experience in the networking industry, focused on Internet infrastructure.
This was first published in September 2003