US 11,812,318 B2
Preserving emergency call during failure to transfer
Jan Hendrik Lucas Bakker, Fort Worth, TX (US)
Assigned to BlackBerry Limited, Ontario (CA)
Filed by BlackBerry Limited, Waterloo (CA)
Filed on May 18, 2022, as Appl. No. 17/747,494.
Application 17/747,494 is a continuation of application No. 16/882,245, filed on May 22, 2020, granted, now 11,343,742.
Prior Publication US 2022/0279411 A1, Sep. 1, 2022
This patent is subject to a terminal disclaimer.
Int. Cl. H04W 36/14 (2009.01); H04W 60/00 (2009.01); H04W 4/90 (2018.01); H04W 36/00 (2009.01); H04W 76/50 (2018.01); H04W 60/04 (2009.01); H04W 76/18 (2018.01)
CPC H04W 36/14 (2013.01) [H04W 4/90 (2018.02); H04W 36/0022 (2013.01); H04W 60/00 (2013.01); H04W 60/005 (2013.01); H04W 60/04 (2013.01); H04W 76/18 (2018.02); H04W 76/50 (2018.02)] 20 Claims
OG exemplary drawing
 
1. A method for transferring an ongoing emergency session from a first network to a second network, the method comprising:
receiving, by the second network from a user equipment (UE), a first attach request message, the first attach request message comprising a PDN CONNECTIVITY REQUEST message with request type set to “handover”;
transmitting, from the second network to the UE, an attach reject message;
receiving, by the second network from the UE responsive to the UE detecting an ongoing emergency session with the first network and in response to receiving the attach reject message from the second network, a second attach request message from the UE, the second attach request message comprising a PDN CONNECTIVITY REQUEST message with request type set to “handover of emergency bearer services” for the ongoing emergency session; and
transmitting, by the second network to the UE, an attach accept message.