Weird MRA unanswered calls (over Expressway) when 4G mobile is used

[Attila Horvath]

Hi, 

We have implemented an Expressway MRA system with CUCM 11.5.

Clients are Android mobile client with newest Jabber. All of clients connecting via MRA (ExpE-ExpC).

When client connected to wireless network (still MRA, over ExpE-ExpC), all of calls will be successful.

But when connected to stable 4G network, sometimes the client cannot ring, just display  an "Unanswered Call" notification.

Tried to debug at CUCM/Expressway pair - and I can see that CUCM sends an 

- INVITE

- Gets back a Trying from ExpC

- after that sends a CANCEL 

Just a note, not all of the time this issue is occured. Sometimes yes, sometimes not.

What could be caused this issue? Why CUCM send Cancel before receive Ringing and 200OK?

Is it a timer? The SIP profile in CUCM is "Standard SIP Profile for Mobile Device" with default values:

(attached)

I assume the internet connection is stable  - as CANCEL arrived in time to client.

[Jonathan Schulenberg]

When comparing a working and non-working example, what’s different in the SIP trace between CUCM and Expressway-C? My guess is that a 183 Session Progress follows the 100 Trying in the working example. If that’a what it is you need to pull logs from the Expressways and Jabber client: did the client ever send one and if yes, did Expressway-E get it? That’s where I would start at least. Keep an eye on the header/SDP differences between working and non-working.

[Attila Horvath]

No, there was not 183 Session in progress, just 180 Ringing - at the successful call.

When call was unsuccesfull, there was not any 180 ringing back, and  CUCM send CANCEL .

If it is a timer, it just occured at mobile calls, as wirelessly connected Jabber clients working definitely well.

Please take a look to the following diagrams (from CUCM trace)

The successfull call was the following:

The Cancel at 11:59:28 is when the caller on-hooked the phone. So this CANCEL was occured by tester staff.

But at the unsuccessfull call, there was not any ringing back, and maybe the Callmanager send a Cancel at 11:59:20 , eight (8) seconds earlier as caller on-hooked call. So this CANCEL was not occured be test-staff, it is occured by Callmanager.

[Dennis Mink]

on the android client, use the "send problem report" option and analyze this, if needed add to this post

[Attila Horvath]

Hi, 

To tell the true - I cannot found any interesting at log. Attached it.

The time when we see a missed call notifocation (as the only one) at client side is:

2018-05-25 11:59:23,164 INFO  [0x00000001b4fb2b40] [miscs/YLCLocalNotificationManager.m(379)] [UI.Action.System] [-[YLCLocalNotificationManager sessionDidEnd:]] - jabber post a notification[You have missed a call] at 2018-05-25 09:59:23 +0000