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SIP trunk setup (CUBE or not)?


I have some basic (I think) questions regarding a SIP-trunk setup to a CUCMBE 6.1.5.

Can I do a straight up authenticated connection from the SIP-provider to the CUCM without use of CUBE in the middle? I have a 2851 router with a E1 talking mgcp with the CUCM as it is now but the customer want to go all out SIP. Since I've got an ip-address from the ISP for use with SIP in a point-to-point connection, can I configure more than 1 interface on the CUCM (as in 1 internal and 1 external (SIP))? The server comes with dual NICs if I'm not mistaken and that could of course do the trick if both are configurable in the CUCM.

If I need the CUBE function, can I use the 2851 as it is now or do I have to upgrade it? I was hoping this was a built in feature in the IOS and "just" a configuration issue if needed.

Please help me out here, I really need your expertise.



Hall of Fame Cisco Employee

The NICs on CUCM servers are only for fault tolerance, they're not meant for any other purpose. You cannot configure different IPs on them, ONLY fault tolerance.

Reasons to terminate a SIP trunk on an enterprise demarc such as CUBE  include but are not limited to:

- Lack of call admission control  (SLA enforcement and DOS attack mitigation) on the SIP trunk

-  Visibility of the CUCM and endpoint IP addresses to the SP network (and  therefore to potential hackers)

- Very limited SIP trunk load  balancing and redundancy capabilities

- No SIP trunk sharing  between multiple CUCM clusters or other IP-PBX/proxy call agents in the  enterprise

- No SIP malformed packet or other protocol level  attack mitigation for your CUCM

- No way to troubleshoot voice  quality problems to determine if it's your network or the SPs network at  fault

- Much more limited toll fraud prevention techniques on the  SIP trunk

- No way to control IP QoS settings on the incoming  packets from the SP, and no way to customize them on the outgoing  packets

- No way to manipulate SIP msging from the SP before it  hits your CUCM to customize it to what CUCM/IP-PBX prefers to see

-  Limited means of complying to the SP UNI (SIP msg manipulation on  outbound msgs to the SP, and capabilities such as early-offer)

-  Having to implement the SP UNI on CUCM instead of your enterprise  preferred policies (and having to replicate this on every CUCM and  IP-PBX routing calls to the SIP trunk)

- Having no way of doing a  SIP registration to the SP when this is required on the SIP trunk

You can use this link to determine the requirements based on what you want to do with the GW:

Software Advisor



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