Disabling call waiting causes SPIP 321 to return Ringing rather Busy to SIP calls.

[cmdrwalrus]

We've disabled call waiting on our 321s running UC 4.0.1B (by setting call.callWaiting.enable="0" in Config/sip-interop.cfg) and noticed a weird effect.  When someone is on a call, and someone else calls their extension, it reports Ringing back to the PBX rather than Busy.  No alerting happens on the callee's phone, but the caller hears ringing on the line.

Why don't the phones report Busy when they're busy?  If they did, the caller would go straight to voicemail rather than having to wait for the ring timeout.

Thanks!

[SteffenBaierUK]

Hello,

looking at the UCS 4.0.1 Admin Guide (as I am unaware of your Software Version) I can see:

The Parameter is for the audible Alerts only as far as I understand.

There is another Part in the Documentation that may give the impression that the phone won't accept second calls but I will discuss this with our documentation department as no signaling is send back to the server if there is a "waiting" call.

Usually the SIP Server should be able to restrict the calls and any addition to the Phones Features would need to be raised via a Feature Request.

Best Regards

Steffen Baier

Polycom Global Services

[cmdrwalrus]

Steffen,

Thanks for the quick response.

The phones are running UCS 4.0.1B.

---

@SteffenBaierUK wrote:

There is another Part in the Documentation that may give the impression that the phone won't accept second calls but I will discuss this with our documentation department as no signaling is send back to the server if there is a "waiting" call.

No, I just tried a quick test, and found that the phone does signal "180 Ringing" back to the server in response to an INVITE when call waiting is disabled and the phone is in use, according to SIP debug output:

<--- SIP read from 10.0.3.78:5060 --->
SIP/2.0 180 Ringing
Via: SIP/2.0/UDP 10.0.0.13:5060;branch=z9hG4bK3b0b6945;rport
From: "chris2" <sip:6220@10.0.0.13>;tag=as7ba3498b
To: "78" <sip:78@10.0.3.78>;tag=7A51F3E8-9A38A47
CSeq: 102 INVITE
Call-ID: 369190f321c8413a4d81fa8e3f8712c2@10.0.0.13
Contact: <sip:78@10.0.3.78>
User-Agent: PolycomSoundPointIP-SPIP_321-UA/4.0.1.13681
Allow-Events: conference,talk,hold
Accept-Language: en
Content-Length: 0


<------------->

My knowledge of SIP signalling is by no means complete, but I would expect it to return "486 Busy Here" in this situation.

Wouldn't you agree that returning "Ringing" when the phone is "Busy" seems outside the norm?

If there's no way for the phones to return Busy, I will have to manage it on the server.  I was hoping to avoid that, but it's definitely a good Plan B.

Thanks for looking into this!

[SteffenBaierUK]

Hi,

yes I am discussing this at present with the Documentation and Development team and I am aware of the SIP Signaling.

I meant no additional message about the disabled call waiting is sent and therefore the caller receives a call progress tone.

Regards

Steffen Baier

Polycom Global Services