[srslte-users] Configuring srsEPC to accept MME unknown UEs

Marek Sebera marek.sebera at gmail.com
Wed Aug 1 10:47:49 UTC 2018

Hi Andre, and all interested,

the important question was buried by other replies, so I post it once more


I'm considering implementing the emergency-attach
procedure, however I'm not sure, how to test it while developing.

I have only one SDR (USRP B210), so I cannot test srsUE against srsENB
using 2 SDRs, what I'd expect be the easiest way to tests/implement.

Do you have any idea, how to simulate emergency attach from real device?

Or if it's possible to work without SDRs, how to run locally srsUE
against srsENB without actually transmitting to the air?


Thank you

On 07/30/2018 10:23 AM, Andre Puschmann wrote:
> Hey,
> the emergency-attach procedure is not supported right. All the documents
> you listed seem to be correct. Needless to say we are happy to review
> pull-requests ;-)
> Cheers
> Andre
> On 28/07/18 11:56, Marek Sebera wrote:
>> Hello,
>> i'm investigating possibility of using srsLTE for disaster relief (ie.
>> when existing PLMNs are over-loaded or their infrastructure fails) and
>> laboratory testing (security testing MEs/UEs without need to change SIM
>> within or degrade from LTE to 3G/2G networks)
>> Reading TS 23.167 (IMS Emergency Sessions) and related parts of 23.401,
>> 24.301, 33.401, and others, it seems that Emergency Session shall allow
>> unauthenticated / unknown UE to access limited or all services, as per
>> network configuration.
>> TR 23.715 specifies RLOS (Restricted Local Operator Services) to
>> Unauthenticated UEs in both IMS and non-IMS attach
>> TS 23.401 section specifies (d) "All UEs are allowed"
>> TS 33.401 section 5.1.3 and 5.1.4 specifies that if UE cannot be
>> authenticated that EIA0 and EEA0 shall be used
>> TS 23.167 specifies that while in Emergency Session the IMS (IP
>> Multimedia Services) could be available
>> So I suspect, that we should be able to configure EPC so, that it
>> provides services (telephony, sms, PDN) to UEs that cannot be
>> authenticated against HSS (user_db.csv).
>> [++++]
>> So the question is: Is it possible to allow unknown UE to access network
>> services, without being previously known to HSS ? If so, how?
>> - If it's possible only for Emergency Session, is it possible to enforce
>> emergency attach from ENB (ie. convert existing standard attach to
>> emergency attach type or let UE know, to repeat attach request in
>> emergency mode?)
>> - If it's possible for normal-style attach, please provide guidance or
>> example configuration
>> [++++]
>> Obviously we could not provide non-NULL EIA/EEA algorithms, because we
>> don't know SIM/USIM Key/OPc and other identifiers
>> And finally, if I just missed the right 3GPP TS/TR document, just point
>> it out, I think, I'm capable of providing implementation within srsLTE,
>> if the process is documented already.
>> Thank you
>> Marek Sebera
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