On 4G "mobile call" you get 8 kpbs - 64 kbps for the voice.
> In fact, VoIP over 4G actually offers higher call quality than standard mobile calling. Mobile calling compresses voice to about 8 Kbps, while VoIP calls can use up to 64 Kbps with a professional provider such as IDT. Instead of the ‘tinny’ voice typical of mobile calls, clients called from VoIP on 4G will hear you clearly.
> In fact, VoIP over 4G actually offers higher call quality than standard mobile calling. Mobile calling compresses voice to about 8 Kbps, while VoIP calls can use up to 64 Kbps with a professional provider such as IDT. Instead of the ‘tinny’ voice typical of mobile calls, clients called from VoIP on 4G will hear you clearly.
https://www.idtexpress.com/blog/difference-3g-4g-voip-calls/