What does CDMA 2000 frame length mean?

Are you talking about the SMS frame length of cdma 2000?

Depending on the length of the short message content and system configuration, the short message can be transmitted on the business channel (basic channel) (Data Burst Message bearer), or on the public control channel (paging/reception) Transmitted (Data Burst Message bearer) on the access channel), the frame length of the access/paging/basic channel is 20ms, but for the access channel, we generally use the access channel time slot (length is 4+PAM_SZ+MAX_CAP_SZ frames), For the paging channel, we use paging slots (4 frames of 80ms). For MT-SMS, the base station will decide whether to transmit the short message on the business channel or the public channel based on the length of the short message. Of course, the base station can be configured to transmit only on the business channel; for MO-SMS, the mobile phone will decide based on the access channel parameters. Message configuration determines the maximum short message length that can be transmitted on the access channel. If it cannot be encapsulated, a service channel needs to be established and transmitted on the service channel. Similarly, the mobile phone can also be configured to transmit only on the service channel. For mobile phones, it is not by actively applying for which channel to use, but by deciding which channel to use for transmission based on the system configuration and the mobile phone's own settings.