I would have never found that by myself!

For next time, here's one relatively easy way to get to a BSP if you know the phone model.

1. Look up the model number in one of the charts on paul-f.com. In this case,

http://www.paul-f.com/we500typ.htm#5252. Read BSP reference numbers in the rightmost column.

3. Enter the BSP number in the search box in the TCI Library.

4. Read the BSP.

Since not all BSPs are in the charts, you may be able to find more references the old-fashioned way:

1. Look in one of the division index documents in the TCI Library. For most telephone sets, use division 502. Later sets (mostly modular and Design Line) are in division 503. Index documents typically end in -000-000, so try these:

502-000-000 503-000-000

General index documents covering all divisions are in 000-000-000 and 000-000-001.

Early 500 sets and earlier sets are in BSPs numbered in an earlier format. Look in the C-series BSPs. Start with C12.001 and C12.101, the general index documents

2. Browse the index for BSPs that relate to the site of interest.

3. Enter the BSP number in the search box in the TCI Library.

4. Read the BSP.

Also posted here for future reference:

http://www.classicrotaryphones.com/forum/index.php?topic=20510.0