> For the complete documentation index, see [llms.txt](https://gsm.learn-telecom.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://gsm.learn-telecom.com/system-information-messages.md).

# System Information Messages

- [System information-1(SI1)](https://gsm.learn-telecom.com/system-information-messages/system-information-1-si1.md): Cell ARFCN, RACH parameters required to access the system by MS and hopping related information are sent in this SI message.
- [System information-2(SI2)](https://gsm.learn-telecom.com/system-information-messages/system-information-2-si2.md): Neighbour BCCH frequencies and PLMN information are sent in this SI. MS uses these frequencies for signal strength measurements required for handover.
- [System information-2bis(SI-2bis)](https://gsm.learn-telecom.com/system-information-messages/system-information-2bis-si-2bis.md): RACH control and BCCH extension on neighbor cells
- [System information-2ter(SI-2ter)](https://gsm.learn-telecom.com/system-information-messages/system-information-2ter-si-2ter.md): Information of BCCH extended allocated on which neighbor cells are provided in this SI. Broadcasted optionally on BCCH by the network to all the MSs.
- [System information-2 Quarter (SI-2Quater)](https://gsm.learn-telecom.com/system-information-messages/system-information-2-quarter-si-2quater.md): 3G neighbor cell related information
- [System information-3 (SI3)](https://gsm.learn-telecom.com/system-information-messages/system-information-3-si3.md): Carry following : 1. LAI of the current location area, 2. Cell identity, 3. Control channel information required to calculate paging group, 4. Cell options to achieve good performance in the cell, 5.
- [System information-4 (SI4)](https://gsm.learn-telecom.com/system-information-messages/system-information-4-si4.md): CBCH and CBCH related frequency information, LAI, Cell selection parameters and RACH control information are carried by this SI4 message.
- [System information-5 (SI5)](https://gsm.learn-telecom.com/system-information-messages/system-information-5-si5.md): It carries neighbor cell informations. In active mode, MS sends measurement reports in the uplink and output power/timing advance information in the downlink (on SACCH). Also gets BCCH carrier related
- [System information-6 (SI6)](https://gsm.learn-telecom.com/system-information-messages/system-information-6-si6.md): Information on LAI, cell options, Cell identity and PLMN permitted or not is transmitted on this SI.
- [System information-7 (SI7)](https://gsm.learn-telecom.com/system-information-messages/system-information-7-si7.md): Cell re-selection parameters needed by MS are sent on this SI.
- [System information-8 (SI8)](https://gsm.learn-telecom.com/system-information-messages/system-information-8-si8.md): Cell re-selection parameters needed by MS are sent on this SI.
- [System information-9 (SI9)](https://gsm.learn-telecom.com/system-information-messages/system-information-9-si9.md): Scheduling related some of the informations are sent on this SI.
- [System information-13 (SI13)](https://gsm.learn-telecom.com/system-information-messages/system-information-13-si13.md): Carry GPRS related information needed for PS call.