While both the methods are pretty good and matured, SCCP integration is best option in my opinion. It is because of a couple of reasons which are as follows:
1)In case of SCCP integration there is 1 to 1 correlation between the voicemail ports on the CUCM and that on Unity Connection. This makes the troubleshooting of Call Flows fairly simply.
Unlike SCCP, SIP integration involves one SIP trunk per unity connection server.
2)The way the MWI dialout works in SCCP integration works is much simpler compared to how it works with SIP.
In SCCP, VM ports simulate a phone extension dialing an MWI on/ off number which is fairly simple to troubleshoot.
In SIP integration, the MWI dialouts are performed using SIP NOTIFY messages.
Having said that, I would again like to emphasize that kind of integration is a matter of choice and convenience.It is difficult to determine one being better over other.
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The only reason I can think of SIP as a preferred integration method is when there is SIP implementation all across in the network as a design requirement.
I remember a case in which customer had SIP implemented all across in his network and thus wanted to have SIP integration between the Call Manager and the Unity Connection.
I believe, an alternative of SIP integration is provided so that Unity Connection can be integrated with other 3rd party SIP based Call Agents/PBXs.
I believe there were quite a few previous threads on this topic you could probably find via. search.
A while ago there was a point where a SCCP integration had an edge over SIP, however now they are basically the same in terms of features. We still implement SCCP simply because it has always worked and there is no specific reason or feature to switch to SIP at this point.
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The answer to this question is a matter of personal preference. I still use SCCP at the moment because, in the past, if you were going to see a bug related to the integration method used then it would likely have been SIP-related and not SCCP. However, there are some that would argue that the SIP integration is "simpler" in terms of configuration. I don't think there really is an argument for one being "better" than the other at this point.
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I would go SCCP, we have an issue with SIP in that it does not use the ‘Voice Mail Box Mask’ from the Voicemail profile when you press the message button. Not a major thing for most people but it is if you used shared mail boxes as our customer did!
We raised a TAC case and were told it was “working as designed” not sure if it was resolved in a later issue. I think this was CUCM 7.1.5.
Hope that helps!
Matty - I have the requirement to use the the "Voice Mail Box Mask" with my customer's CUCM/UC integration. All phones are 9971's (SIP signaling) and I've had DTMF issues with UC when setting up the ports in SCCP, so I switch over to SIP trunk. When I tested the SIP integration, I ran into the same issue you ran into with "Voice Mail Box Mask" not working. With CUCM 8.6(2a) doesn't look like the "issue" has been fixed. Can you send me your TAC case number? I'm going to open another ticket and reference your case to see if there is maybe an enhancement bug filled for this "issue".
Unfortunately I don’t work for the same company anymore and the TAC case number would be on their CRM system.
I had a look through some archived emails and I do have a work around that I found I can share this with you if it is any use?
Sorry for the delay! Below is the work around that I tested in our lab at the time.
The problem appears to be the ‘Voicemail Profile’, ‘Voice Mail Box Mask’ is only used on the call forward and not when the message button is press.
In the example ext 3012 has a voicemail box setup in Unity with extension 5553012. The default voicemail number is 8000.
Below profile for users with mailbox’s beginning 555:
8001 is a translation pattern. This transforms the Calling Party to prepend the 555 when the message button is pressed, before passing the call into Unity via the usual 8000 pilot:
Hope that helps!
I would choose SCCP for this reason: CLID on calls originating from Unity Connection, such as notification dial-outs. I like to be able to set this to the main Unity Connection pilot number, so that users can see where the call is coming from, and call back to Unity Connection easily if they miss the notification call. This is stupid simple with an SCCP integration, just by setting the External Number Mask on the Voice Mail Ports. With SIP, there is no setting for the CLID in CUCM or in Unity Connection. The only way I've been able to set CLID in Unity Connection using SIP is by implementing a very complicated workaround, involving calling-number-routed translation patterns, which isn't very supportable for someone else coming in to troubleshoot.
CUC Admin > Telephony Integrations > Port Group > [Your Port Group] > Contact Line Name
Set this to a telephone number and CUC will use it for outbound caller ID.