	US 12,016,070 B2
	Efficient evolved packet system (EPS) fallback
Rahul Pal, Bellevue, WA (US); Suresh Thanneeru, Redmond, WA (US); Salvador Mendoza, Issaquah, WA (US); and Karunakalage Viraj Rakitha Silva, Renton, WA (US)
Assigned to T-Mobile USA, Inc., Bellevue, WA (US)
Filed by T-Mobile USA, Inc., Bellevue, WA (US)
Filed on Nov. 14, 2022, as Appl. No. 17/986,750.
Application 17/986,750 is a continuation of application No. 16/376,809, filed on Apr. 5, 2019, granted, now 11,510,267.
Prior Publication US 2023/0075268 A1, Mar. 9, 2023
This patent is subject to a terminal disclaimer.
Int. Cl. H04W 76/18 (2018.01); H04L 12/66 (2006.01); H04L 47/20 (2022.01); H04W 8/02 (2009.01); H04L 65/1016 (2022.01)

CPC H04W 76/18 (2018.02) [H04L 12/66 (2013.01); H04L 47/20 (2013.01); H04W 8/02 (2013.01); H04L 65/1016 (2013.01)]

20 Claims

1. A session management system, comprising:

at least one processor; and

at least one memory storing instructions, the instructions being executable by the at least one processor to perform operations comprising:

transmitting, to an Access and Mobility Management Function (AMF) in a 5th Generation (5G) network, a first request to set up a call in the 5G network;

receiving, from the AMF, a first rejection message that indicates a rejection of the first request by a 5G Radio Access Network (RAN) connected to the AMF;

in response to receiving the first rejection message, transmitting, to a Mobility Management Entity (MME), a second request to establish a first dedicated bearer through a 4th Generation (4G) network; and

after a predetermined time after transmitting the second request, transmitting an indication of a call failure to a policy control function (PCF) or a policy and charging rules function (PCRF).