VoLTE: Why UE is not sending PCO option in attach request?

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Samsung UE is not sending PCO option during attach request and as a result P-CSCF discovery is not working?

Is there a specific NV item to be changed or any config change to be made? This is a commercial UE and OS is Android 5.0

posted Apr 14, 2015 by Alkesh Mehta

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1 Answer

Hello Alkesh,

The UE should request for DNS Address and PCSCF Address via sending PCO in Attach Request. The UE request with ProtocolId value 1 (for PCSCF Address) and 2 (DNS server address). But the ProtcolIDvalues will be empty. Since UE is asking these Values from network. Is this happening in your case? or UE itself not include whole PCO?
Hence NW will include these values in PCO while sending ActivateDefaultEPSbearerContextRequest Message.

answer Apr 22, 2015 by Anand Yadav

Thanks Anand.

UE is not including PCO option for P-CSCF in attach request.

commented Apr 22, 2015 by Alkesh Mehta

You mean to say.. whole PCO is coming as omitted in Attach request?
So during Initial Attach itself are you attaching with IMS PDN?

commented Apr 22, 2015 by Anand Yadav

yes initial attach with IMS pdn.

commented Apr 22, 2015 by Alkesh Mehta

Ok.Thanks.
I am not sure whether you can access NV items ,since its a commercial device . But we also uses Samsung devices and they works fine with respect to PCO filed.You need to contact Samsung Team to insert a Binary in the device to populate PCO

commented Apr 22, 2015 by Anand Yadav

NV items accessible. Can you suggest which NV to refer.

commented Apr 22, 2015 by Alkesh Mehta

I am not sure with respect to NV Item. Could you please check the PCO fields in the ESM Information Response Message as well. Whether PCO is included in it? Is VoLTE/IMS enabled on the UE?

commented Apr 22, 2015 by Anand Yadav

PCO field is not included. it marked as 0
prot_config_incl =0

VoLTE/IMS is enabled on UE

commented Apr 22, 2015 by Alkesh Mehta

Ok. What if you send PCO in ActivatedefaultEPSbearerContextRequest. Doe UE Starts PCSCF discovery via SIP Register?

commented Apr 22, 2015 by Anand Yadav

NW expects PCO request from UE so when it doesn't get it does not send PCO in default bearer request

commented Apr 22, 2015 by Alkesh Mehta

Ok..So you dont have control on Network. I am not sure Alkesh better to ask Samsung Team

commented Apr 22, 2015 by Anand Yadav

thanks Anand for your help.
I suspect its UE issue so let see if we get new update or firmware.

commented Apr 22, 2015 by Alkesh Mehta

Yaa..That may help.

commented Apr 22, 2015 by Anand Yadav

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