Granted Patent B2

US 12,520,381 · App. 18/251,780 · Granted Jan 6, 2026

Inventors: Shashanka Totadamane Ramappa (Shivamogga, IN); Krisztian Kiss (Rancho Santa Fe, CA); Madhusudhan Cheripally (Bengaluru, IN); Michael Lee (San Diego, CA); Pradeep Pangi (Bengaluru, IN); Rajkumar Krishnaperumal (Bengaluru, IN); Sridhar Prakasam (Fremont, CA)

Assignee: Apple Inc.

H04W76/50H04W76/18

Abstract

Claims (28)

1 . A method performed by a wireless device for establishing a voice call, the method comprising:

receiving an indication that a first wireless system supports emergency service fallback;

receiving an indication to establish an emergency voice call;

transmitting an emergency service request to the first wireless system;

determining that an unexpected error has occurred, wherein the determining comprises determining that a network congestion timer is running;

selecting a second wireless system based on the determination that the unexpected error has occurred; and

connecting to the second wireless system to complete the emergency voice call.

2 . The method of claim 1 , wherein the first wireless system comprises a 5G new radio (NR) wireless system, and wherein the second wireless system comprises a 4G long term evolution (LTE) wireless system.

3 . A wireless device comprising:

an antenna;

a radio operably coupled to the antenna; and

a processor operably coupled to the radio,

wherein the wireless device is configured to:

receive an indication that a first wireless system supports emergency service fallback;

receive an indication to establish an emergency voice call;

transmit an emergency service request to the first wireless system;

determine that an unexpected error has occurred, wherein determining comprises determining that a network congestion timer is running;

select a second wireless system based on the determination that the unexpected error has occurred; and

connect to the second wireless system to complete the emergency voice call.

4 . The wireless device of claim 3 , wherein the first wireless system comprises a 5G new radio (NR) wireless system, and wherein the second wireless system comprises a 4G long term evolution (LTE) wireless system.

5 . A non-transitory computer-readable medium that stores instructions that, when executed, cause performance of the following actions by a wireless device:

receiving an indication that a first wireless system supports emergency service fallback;

receiving an indication to establish an emergency voice call;

transmitting an emergency service request to the first wireless system;

determining that an unexpected error has occurred, wherein determining comprises determining that a network congestion timer is running;

selecting a second wireless system based on the determination that the unexpected error has occurred; and

connecting to the second wireless system to complete the emergency voice call.

6 . The non-transitory volatile computer-readable medium of claim 5 , wherein the first wireless system comprises a 5G new radio (NR) wireless system, and wherein the second wireless system comprises a 4G long term evolution (LTE) wireless system.

Assignments (1)

Priority Claims (1)

Continuity (1)

References Cited (10)