| CPC H04W 60/00 (2013.01) [H04L 65/1104 (2022.05); H04M 7/123 (2013.01); H04M 7/1235 (2013.01); H04W 8/24 (2013.01); H04L 65/1016 (2013.01); H04W 76/10 (2018.02)] | 20 Claims |

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1. A method comprising:
establishing, by a user equipment (UE), a connection with a wireless network using a radio access technology;
receiving, by the UE, over a first transport, a first Session Initiation Protocol (SIP) message from the wireless network including a first request to establish a service with the wireless network using the first transport;
determining, by the UE, that the service cannot be established using the first transport based on memory-stored information including a policy associated with the radio access technology;
sending, by the UE, a second SIP message to the wireless network including an indication that the first request has been rejected, wherein the indication comprises a second transport;
in response to the second SIP message, receiving, by the UE, over the second transport, a third SIP message from the wireless network including a second request to establish the service with the wireless network using the second transport;
determining, by the UE, that a change of communication capabilities of the wireless network has occurred; and
in response to the determining, sending, by the UE, a fourth SIP message to the wireless network, wherein the fourth SIP message indicates a need to transfer the service.
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