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What is the difference between User-Equipment-Info and IMEI AVP?

+4 votes

When I come across the S6a interface we are using IMEI AVP for International Mobile Equipment Identity.

But when I come across the Gy interface we are using a Grouped AVP named as User-Equipment-Info AVP which contain User-Equipment-Info-Value and User-Equipment-Info-Type.

My query is why we need to use two different Diameter AVPs across the EPC network which gives the same result , let say IMEI in this case.

posted Dec 17, 2015 by Chinmoy Padhi

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Hi Chinmoy,
Good question. I think this wil help me a lot
I have basic knowledge of S6a, but now looking in the Gy.
I think S6a spec is based on LTE 3gpp AVPs (i.e from the 3gpp dictionary).
But the Gy is based on the RFC 4006, which is base AVP.. So this User equipement may be generic term for the terminal (whether the Mobile, or the any other node).
Please correct me, i am naive in this area..

thanks a lot
As per my understanding the difference is that Gx and Gy interfaces can be used with various other than LTE network also. The user can use any kind of equipment so a generic AVP is used. However MME is used with only LTE network and hence the granular AVP IMEI is used.

Peeyush Sharma
Hi Priya,
Gy follows both 3GPP 32.299 and rfc 4006.Moreover,User-equipment-info and imei avp follows 3GPP TS 23.003.same explanation can be found at 3GPP 29.272 and 3GPP TS 32.299
Thanks Peeyush for your answer.
But with your answer I got curious can both these avps be swapped at S6a/S6d and Gy interfaces
I believe that is not possible. Gy interface is basically derived from Ro interface. In IMS network a user can you any device like Cellphone, Laptop, Tablet etc to use its services so a generic term User-Equipment-Info can only help. However when user is trying to connect to a LTE network using MME in that case that device should have a valid IMEI number

Peeyush Sharma

1 Answer

0 votes

Even I have the same understanding what Peeyush and Priya have.
S6a interface is 3GPP defined between the MME and the HSS.
It is mandatory to have a valid IMEI AVP for a mobile which wants to connect LTE network.
While other AVP is generic one and it may be used for various types of devices , mobile could be one of those device.

answer Dec 17, 2015 by Vimal Kumar Mishra
Thanks Vimal, but I have a query since S6a used for LTE while for legacy network (2G/3G) we use S6d. In both these interfaces we use IMEI AVP. So what my opinion is it is hard to say that IMEI AVP Needs to be part of only LTE network and not for legacy network.
please correct me if I am wrong
In legacy network also user can be validated with IMSI and device information is also needed which comes from IMEI.
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