VG224 MGCP vs. SCCP

Unanswered Question

Hello all,

I have always used MGCP when configuring my gateways with PRI's. I am looking for some advice on whether to use MGCP or SCCP on 8 VG224s I am installing. I have seen some posts in the forums that SCCP has more features, but I could not find any documents that compare the features.

I would be happy to hear your opinions on what you are using and why or any links to side by side comparisons.

In the end, unless SCCP has a substantial amount of features over MGCP, I would probably stick to MGCP.

Thank you,

Heath

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dc-csa-north Tue, 05/26/2009 - 21:25

Hi,

The best of the two options would be mgcp,i have been using mgcp with vg224 for last of my two clients.

dc

Nicholas Matthews Wed, 05/27/2009 - 04:46

Here's the list of SCCP FXS features:

http://www.cisco.com/en/US/docs/ios/voice/fxs/configuration/guide/fxshist.html

There's a lot of things you can do with SCCP that you can't with MGCP. Park, pickup, hold, transfer, conference, etc. Almost everything you can do with an IP phone you can do using codes on the phone. You use hookflash for holds/transfers and then dial things like **7 to use a certain feature.

-nick

Tommer Catlin Tue, 06/23/2009 - 10:43

Great post Nick. Question for you... My customer is has a mix of uses for the VG224s we are going to install. Primarily, it will be setup with this:

7945 phone Line 1 x4000

VG224 Port 1 x4000

So basically it is a shared line between the analog port and the IP phone. The thought is that the client could plug in an analog phone and be able to answer either their IP phone or the analog set. But what throws a wrench is that, it is possible that the analog be used for faxing instead or also for the analog phone.

Would SCCP be better or MGCP?

Thanks much!

Nicholas Matthews Tue, 06/23/2009 - 17:19

Hi Tommer,

This depends. I would say SCCP is probably better at handling shared lines than MGCP, but MGCP will have greater faxing capability.

If you are forced to do IP faxing to a 3rd party device in your network or SIP trunk, I would go with MGCP. If you know that every time you're going to fax to a Cisco device on the other end of the IP leg, go with SCCP and configure modem passthrough.

-nick

Tommer Catlin Tue, 06/23/2009 - 19:36

Thanks Nick. I saw that SCCP does T.38 so that should be ok correct? The provider has some soft switch on the backend, but my PRIs are mgcp off 2851 coming in. So it would be MGCP at the gateway, then SCCP at the VG224.

I agree with the SCCP and the shared lines. They will probably have around 10 fax machines, but who knows. It's a residential complex. So a resident could in theory, plug in a fax machine instead of an analog phone.

lfulgenzi Wed, 05/27/2009 - 13:34

It all depends what you're using the gateways for. If it's primarily analog phones, go with SCCP. When you configure FAX/modem passthrough, even modems and faxes will work without too many issues.

The big thing is contact enabled alarms. This needs MGCP as far as I know, otherwise you lose the location information of the alarm.

In that case, buy a vg202/4 for the few alarms you have or a separate vg224 for alarms only and config that as MGCP.

Thank you all for your responses. I am going to be using this primarily for fax and modems. I was looking into using SCCP so I could still use conferencing on our Analog Polycom units, but it looks like even SCCP has a 3 party limit unless using meet-me conferencing (which we use conf. services for this type of conf.) I am going to go ahead and use MGCP and replace the Polycom units with 7936's

Thanks again,

Heath

ausjustin Thu, 10/21/2010 - 22:12

for the fax via sip trunk and so  we have use MGCP , but some feature we have use SCCP .

my question is can we use MGCP and SCCP on the same VG224 ?

Is it working this way ?

thanks

Ray Watkins Sat, 10/23/2010 - 18:20

Yes as long as you're not trying to control the same port with both protocols.

birnit Tue, 01/10/2012 - 09:39

How can you configure a protocol on a port different than that of the gateway.  The port comes up with the default protocol set for the gateway.  I would like to configure an mgc port on a VG224 set up with SCCP protocol.

Steven Holl Mon, 10/25/2010 - 07:47

Yeah (just to clarify for others here) you want to keep your fax machines off of SCCP if you have a SIP trunk to an ITSP.  That will be protocol-based switchover, which a SCCP port cannot do, but MGCP, H323, SIP endpoints are able to.

Jeremy Combs Wed, 12/01/2010 - 06:13

Steve, I was in RTP last week and you weren't there!  Hey, interesting comment on not using SCCP if you are using SIP Trunks to the provider.  I'm running SCCP VG224s with CUCM 6, with SIP Trunks into my ISR G1 and G2s and then ISDN PRIs out to the PSTN with no issue.  (We are using SIP due to CVP).  How have you experienced problems with this?

Steven Holl Wed, 12/01/2010 - 06:56

Hey Jeremy,

Yeah, I was away for Thanksgiving last week.

The reason I don't recommend SCCP on VGs if a SIP ITSP is being used is for faxing.  The SCCP controlled endpoints only can switchover with NSEs, and providers need to see a protocol-based switchover.  With MGCP/SIP/H323, the VG can use a protocol-based switchover to trigger a SIP re-INVITE for 711 or T.38 to the provider.

If you're just using the VGs for voice, or don't fax out the SIP ITSP, feel free to use SCCP on the VGs.

seanboulter Thu, 12/09/2010 - 09:59

All of our VG224s have a mix of fax and analog phones.  I'v been looking into SRST and the only config I can find is with SCCP.  Is that true, or can you do SRST with MGCP?

Steven Holl Thu, 12/09/2010 - 14:18

You can get call preservation & SRST-like functionality on your MGCP FXS endpoints.  Treat it like you would an MGCP PRI which you want call preservation enabled (i.e. 'call application alternate default') .  Then you also need to have lower preference dial-peers pointing to your SRST gateway via SIP or H323.  Just make sure you don't create dial-peers without 'service mgcpapp' which get matched when you go offhook in normal mode.

Jeremy Combs Thu, 12/16/2010 - 06:57

Steve,

Do you know if there is a (enhancement) bug out there on this or if or when the BU plans to add protocol switchover support to SCCP for T38?

Steven Holl Thu, 12/16/2010 - 07:04

jeremy.combs wrote:

Steve,

Do you know if there is a (enhancement) bug out there on this or if or when the BU plans to add protocol switchover support to SCCP for T38?

That will likely never happen.  The SCCP protocol currently doesn't have any provisioning for protocol-based switchovers.  It would have to be added to the SCCP protocol in a later protocol revision, and then that version would have to be reflected in CUCM and the gateway code.

What would be more likely as a feature request would be IOS MTP or CUBE  support to convert an NSE switchover to a protocol switchover (and  vise-versa).  That would be a cool function, and logically would work.

I encourage you to have your account team file a PERS request for either of these, though.  If there is enough interest, they may be some traction to get that to happen.

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