Switching to VoIP

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Chapter 7: Replacing Call Signaling with VoIP

These protocols don’t tend to be as practical when used as endpoint-signaling proto-

cols as they are when used as trunk and gateway ones. When an administrator needs to

alter the configuration of a MEGACO device, he may have a tendency to “set it and

forget it,” because changes to trunks and gateways are typically rare compared to end-

point changes. This isn’t to say that there aren’t any MGCP-based IP phones, because

there are. But the realm of IP phone and softPBX signaling favors H.323 and SIP.

The day-to-day administration required for enterprise VoIP leans more heavily

toward the endpoint-to-endpoint, not gateway-to-gateway, communications, just as

in traditional telephony. As a result, most enterprise administrators will spend the

bulk of their time working with H.323 or SIP devices.

H.323, SIP… How Do I Choose?

More often than not, if you’re using a commercial VoIP platform to build your net-

work, the choice will already be made for you. If you’re using a Cisco CallManager

softPBX, then you probably aren’t going to be using SIP, because CallManager’s SIP

support is far from complete for even mundane telephony apps. (CallManager uses

Cisco-proprietary SCCP signaling instead.)

Regardless of how well each vendor claims to support ...