ike us, which is why SO many companies are pursuing this model. A non-CME SIP environment is shown in Figure 30-6. In this case, the phones register directly with the SIP provider's SIP proxy. Since there are no CMEs involved, SCCP is no longer used. If you're building or experimenting with a SIP-only solution using Cisco IP phones, you may have to load SIP-based firmware on them. Check Cisco's website to see how to accomplish this. Many newer Cisco phones are SIP-based, SO check carefully if you're buying used. In this case, all PBX functionality-from extension provisioning to voicemail and be- yond-is handled by the provider in the cloud. Configuration is generally done by Chapter 30: VolP Figure 30-6. Two offices using SIP phones without CME minimally trained users through the provider's web page. If you have Vonage or Magic Jack or something similar, you are using this model. Many executives love this idea, as evidenced by the many SIP providers that have entered the game in the past few years. I've seen companies with over 100 employees use this type of service successfully. For our example, I'm going to build a SIP trunk into the cloud for our CME system. We'll get a SIP trunk or two from a SIP provider and configure the system to use these trunks for incoming and outgoing calls. The network will resemble what's shown in Figure 30-7. Figure 30-7. SIP trunk for outside lines The first thing to do is get the information regarding the trunks from the SIP provider, who will likely provide you with a phone number for inward dialing, a username, and a password. The username and password may also be called an authname and key. For our two SIP trunks, we've been given the following information: SIP Proxy information SIP-Proxy: sbc.sip-provider.com Trunk1 Number: 9735554222 Authname: 557333333 Small-Office VolP Example Key: 123456789 Trunk2 Number: 9735554333 Authname: 608222222 Key: 123456789 This information will allow us to authenticate to the SIP proxy in order to register our trunks for incoming calls, and to a