[Spce-user] SPCE V3 with SBC

John Murray john.murray at skyracktelecom.com
Mon Oct 28 08:18:01 EDT 2013

Thanks for the detailed reply Andreas.

I am using the Frafos ABC SBC so should be pretty flexible regarding header

The 2 main problems I had were:

- We have 3 inbound call types 1)From PSTN peers 2) From registered UAs
2)From trusted sources
  When all three came from the same address calls would all be classified as
'from PSTN' but I guess in 3.1 the
  P-NGCP-Src-* set in the SBC will fix that. Currently we just use 2
addresses on the SBC, one for peers and one for UAs/Trusted sources.
- It seems to make sense also to offload media from SPCE if possible. Will
the SPCE just drop the call if it sees no RTP?

Best regards


-----Original Message-----
From: spce-user-bounces at lists.sipwise.com
[mailto:spce-user-bounces at lists.sipwise.com] On Behalf Of Andreas Granig
Sent: 28 October 2013 11:58
To: spce-user at lists.sipwise.com
Subject: Re: [Spce-user] SPCE V3 with SBC


On 10/25/2013 03:48 PM, John Murray wrote:
> I am deploying a SBC in front of my SPCE for both Registration 
> offload/NAT traversal and Peer management.
> Are there any recommendations for this?
> I have one problem that INVITES from both registered handsets (UAs) 
> and peers now come from the same address to the SPCE which leads it to 
> see ALL calls as from the PSTN.
> Any suggestions? I guess I could have different ip addresses or ports 
> on the SBC for the different traffic types.

At least for peerings, we'll have a new option in the upcoming 3.1 release
to force outbound calls to peers via a specific hop between the lb and the
peer (in our case we implemented it specifically to define an SBC there).

So if you have 2 SBCs between the SPCE and your peer, you'll add your
peering server twice, once with a route via SBC1 and once with a route via

For outbound calls, the SIP message will be rewritten by proxy/lb to insert
an additional Route header pointing to the SBC. For inbound calls, the lb
will take the P-NGCP-Src-* headers provided by the SBC (you've to configure
the SBC to pass ip, port, proto etc in these
headers) in the lb config and pass it on to the proxy, instead of putting
the socket info there.

For calls from/to local subscribers, there is nothing to do on the SPCE
anyways, as the UAs need to be configured to send their traffic to the SBC,
and the SBC needs to forward it to the SPCE. The SBC can then either insert
a Path header in the REGISTER, or it puts itself into the Contact. Either
way will work.

We're currently preparing/testing 3.1-rc1, so 3.1 final is just around the


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