106 Chapter 8 Installing a media bay module (MBM)N0060612N0060612Figure 64 Process for determining MBMsThe first step in selecting the MBMs is to establish the number of extensions (internal lines) andPSTN lines (trunk lines) you have or need. This step allows you to determine the number and typeof MBMs you require. The following sections describe how to determine which MBMs, and howmany, you require for your system.• “Selecting trunk MBMs” on page 106• “Selecting station MBMs” on page 108• “Selecting a fiber expansion module (FEM)” on page 109After you determine the MBMs required, calculate how the MBMs use the available systemresources. The following sections describe how the MBMs work within the available channels onthe media services card (MSC) in the BCM system.Selecting trunk MBMsThe number and type of lines coming into your system determine which trunk MBMs, and howmany MBMs, you require to support your needs. Trunk lines come from the public network(PSTN) or they support connections in a private network.If you are setting up an entirely new system, perform a site survey to determine your current andfuture needs. Nortel recommends that you perform the survey before you order any MBMs.To select trunk MBMs1 In Table 25, record the number of each type of line you have. If you do not know the numberor type of lines you have, contact your service provider.Note: If you plan to add any lines in the near future, include them in your initial estimates.Determine DS30requirements foreach MBMDetermine if anyoffsets can be usedSet DIP switches onMBMsInstall MBMs into the mainunit or expansion unitDetermine trunkand extensionrequirementsDetermine whichDS30 buses areavailable
