Improving voice over internet protocol (voip) call setup success rate and latency

An apparatus for wireless communication by a user equipment (UE), comprising:

• a memory;
• at least one processor coupled to the memory;
• and
• instructions stored in the memory and operable, when executed by the processor, to cause the apparatus:
• to attempt a mobile originated voice over Internet Protocol (VOIP) call across a packet switched network with a first transmission control protocol (TCP) connection of an Internet Protocol multimedia subsystem (IMS) session;
• to perform a silent redial of the mobile originated packet switched call via a circuit switched network, in response to a failure of the mobile originated packet switched call;
• and
• to transmit a keep alive message over the packet switched network after terminating the circuit switched network call and reconnecting to the packet switched network.

An apparatus for wireless communication by a user equipment (UE), comprising:

• means for attempting a mobile originated packet switched call across a packet switched network with a first transmission control protocol (TCP) connection of an Internet Protocol multimedia subsystem (IMS) session;
• means for performing a silent redial of the mobile originated packet switched call via a circuit switched network, in response to a failure of the mobile originated packet switched call;
• and
• means for transmitting a keep alive message over the packet switched network after terminating the circuit switched network call and reconnecting to the packet switched network.