SRST with SIP CUBE

[glennmartindell]

Hello All,

I have a SIP to SIP CUBE router with a SIP trunk to the PSTN.   This router is also acting as an SRST gateway for the local site for about a dozen 7841 phones (SIP).   Everything is working well in both SRST and non-SRST modes except when in SRST I have the following issue:

Phone A forwards their phone to Phone B

When calling from phone C to phone A, the call forwards correctly to phone B

When calling from the PSTN to Phone A, nothing happens.   No ringback, no forwarding, no nothing.   Is there something I need to put in my config to allow forwarding from a PSTN SIP trunk to a SIP phone in SRST?

Thanks,

Glenn

[Mohammed al Baqari]

Hi,

Try to disable supplementary-service

voice service voip

 no supplementary-service sip moved-temporarily

If didn't work, try to get debug ccsip mess during call forwarding.

[craigneeld]

Support for CUBE and SRST is planned for November 2017. Apparently it will be a phased roll-out with basic calling first followed by more functionality in later releases.

[Yorick Petey]

Hi Craig,

Where did you get this info?

MP me if you prefer.

Thank you!

[craigneeld]

Hey Yorick,

   We got it directly from Cisco via our A.M.

Hope this helps!

C

[Yorick Petey]

Thank you Craig!

[Jonathan Schulenberg]

I'm not saying you can't make it work but for the record, combining CUBE and SIP SRST on the same router is categorically not supported by Cisco at this point.

[glennmartindell]

Hi Jonathan,

Thanks for the reply.   It looks like there is some conflicting information about if this is supported or not.   From "Best Practices When Implementing SIP Trunks for PSTN"

http://www.cisco.com/c/en/us/products/collateral/unified-communications/unified-border-element/white_paper_c11-620461.html

SBC Best Practices

Best practices in the area of SBC deployment include:

● For small-site (or remote-office) SBC deployments that carry low traffic, use a single Cisco router with integrated services such as Cisco Unified Border Element, MTP, VoiceXML, firewall, and Survivable Remote Site Telephony (SRST) features.

I also found another discussion with the attached picture

https://communities.cisco.com/thread/28883?tstart=0

Thanks,

Glenn

[Jonathan Schulenberg]

Some of that information is from the era where all phones were SCCP. The combination of SCCP SRST with CUBE on ISR G2 is the only currently supported combination. The rest you can chalk up to things slipping through the cracks.

There is no conflicting information as of today: CUBE and SIP SRST aren't supported co-resident on any platform. CUBE and SRST - either SIP or SCCP - aren't supported on ISR 4k. I have been told this first-person by both the PM and TME supporting CUBE. Some feature/call combinations will work but not all of them and since the developers weren't asked to explicitly build for and test that combination they can't be asked to support them after the fact. The product manager has to put that effort on the product development roadmap and commit hours/dollars to get it done. Anything forward-looking is NDA-protected so I can't speak to it here. You can reach out to your Cisco AM with any questions on that front.

[AbteenZ]

Thanks for the great Info.

So how can we have SRST with outgoing call flow to the Same SIP Trunk?

[AbteenZ]

What about Q13 on this page?

https://supportforums.cisco.com/document/69976/frequently-asked-questions-cisco-unified-border-element-cube#Q3:_How_the_Media_is_handled_in_CUBE_

[Jonathan Schulenberg]

That document is incorrect. It is not written by the Cisco product team and will not be considered authoritative by Cisco TAC.

[Zekeria Sammantar]

I was almost going to implement this on C3945E-CME-SRST/K9 ISR G2 but I'm awaiting confirmation from this Cisco AM as it already December and I cant find it listed as a new feature on the latest SRST version.

Thanks for helping me dodge the bullet.

[Jonathan Schulenberg]

To keep everyone updated, CUBE and SIP SRST are now supported co-resident on the same ISR 4000 series router beginning with IOS XE 16.7.1. The key feature that allowed this to happen is SIP multi-tenanancy, allowing the line- and trunk-side SIP feature sets to coexist without stepping on one another. Additional detail is provided in the CUBE Configuration Guide Supported Platforms chapter and SRST System Administrator Guide Configuring SIP Trunking on Unified SRST chapter.

In my opinion, we're unlikely to see SCCP co-residency added in the future. My impression is that Cisco has consolidated all future development effort on SIP, likely as a pragmatic realization that they can't keep up by keeping all of the "legacy" protocols afloat. Again, that's only my opinion.

[joeg]

Hi Jonathan,

Cisco has listed here https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/voice/cube/configuration/cube-book/supported-platforms.html?bookSearch=true that Unified SRST colocation with CUBE is supported on G2 routers for SCCP: "SCCP SRST is supported."It states "SIP SRST is not supported."  Is this incorrect?