Section: 10.5.4.25 User-user
Content: The purpose of the user-user information element is to convey information between the mobile station and the remote ISDN user. The user-user information element is coded as shown in figure 10.5.114/3GPP TS 24.008[ Mobile radio interface Layer 3 specification; Core network protocols; Stage 3 ]  and table 10.5.131/ 3GPP TS 24.008[ Mobile radio interface Layer 3 specification; Core network protocols; Stage 3 ] . There are no restrictions on the content of the user-user information field. The user-user is a type 4 information element with a minimum length of 3 octets and a maximum length of either 35 or 131 octets. In the SETUP message the user-user information element has a maximum size of 35 octets in a GSM PLMN. In the USER INFORMATION, ALERTING, CONNECT, DISCONNECT, PROGRESS, RELEASE and RELEASE COMPLETE messages the user-user information element has a maximum size of 131 octets in a GSM PLMN. In other networks than GSM PLMNs the maximum size of the user-user information element is 35 or 131 octets in the messages mentioned above. The evolution to a single maximum value is the long term objective; the exact maximum value is the subject of further study. NOTE: The user-user information element is transported transparently through a GSM PLMN. Figure 10.5.114/3GPP TS 24.008[ Mobile radio interface Layer 3 specification; Core network protocols; Stage 3 ]  User-user information element Table 10.5.131/3GPP TS 24.008[ Mobile radio interface Layer 3 specification; Core network protocols; Stage 3 ] : User-user information element