A method performed by a User Equipment, UE (102, 600), the method comprising: identifying a policy indicating a first dedicated bearer associated with a first guaranteed Quality of Service, QoS, level is network-initiated, the first dedicated bearer being used to establish voice services through a core network and an Internet Protocol, IP, Media Subsystem, IMS, network; initiating (218, 202, 232) a call by transmitting a first Session Initiation Protocol, SIP, message to the core network, the first SIP message requesting the voice services from the core network and the IMS network; receiving (206, 220, 234) a second SIP message from the core network; in response to the second SIP message being received as a dedicated bearer establishment request message including a request to establish the dedicated bearer, triggering a timer associated with a wait time to start; determining, as an expired timer, the timer at expiration of the wait time, without a confirmation of establishment of the dedicated bearer associated with delivery of the voice services through the core network and the IMS network having been received; andin response to the expired timer being associated with a start time at which the dedicated bearer establishment request message has been received, and an expiration time at which establishment of the first dedicated bearer has not been confirmed, initiating (214, 224, 238) a fallback option for the call, wherein initiating the fallback option comprises transmitting, to the core network, a request for a second dedicated bearer associated with a second guaranteed QoS level, the second guaranteed QoS level being lower than the first guaranteed QoS level; receiving a confirmation of the second dedicated bearer from the core network; and receiving the voice services from the core network via the second dedicated bearer. identifying a policy indicating a first dedicated bearer associated with a first guaranteed Quality of Service, QoS, level is network-initiated, the first dedicated bearer being used to establish voice services through a core network and an Internet Protocol, IP, Media Subsystem, IMS, network; initiating (218, 202, 232) a call by transmitting a first Session Initiation Protocol, SIP, message to the core network, the first SIP message requesting the voice services from the core network and the IMS network; receiving (206, 220, 234) a second SIP message from the core network; in response to the second SIP message being received as a dedicated bearer establishment request message including a request to establish the dedicated bearer, triggering a timer associated with a wait time to start; determining, as an expired timer, the timer at expiration of the wait time, without a confirmation of establishment of the dedicated bearer associated with delivery of the voice services through the core network and the IMS network having been received; andin response to the expired timer being associated with a start time at which the dedicated bearer establishment request message has been received, and an expiration time at which establishment of the first dedicated bearer has not been confirmed, initiating (214, 224, 238) a fallback option for the call, wherein initiating the fallback option comprises transmitting, to the core network, a request for a second dedicated bearer associated with a second guaranteed QoS level, the second guaranteed QoS level being lower than the first guaranteed QoS level; receiving a confirmation of the second dedicated bearer from the core network; and receiving the voice services from the core network via the second dedicated bearer.