Can DLU be connected to LTGF?

Some friends have a former DIVF (Fernvermittlung), which obviously did not natively have any direct subscriber lines attached; rather, as a DIVF it was only interconnected via trunks to other switches.

They have several racks labelled “LTGF”, which each seem to consist of six shelves, each containing the following components:

  • 4x DIU 39D
  • TOG A2
  • SPMX A
  • LIU
  • SMXC
  • GCG LTGY
  • PMU0

This seems substantially different from the LTG that we have seen in other EWSDs, as documented at EWSD-LTG - Retronetworking - Open Source Mobile Communications

Now the question is: Can one use those LTGF to connec to DLU at all? Or would one have to swap some components? Or would one have to replace the entire LTGs with different ones as used at DIVO configurations?

@jolly @juergen_lanzki @Radiomann @jpesak - any ideas?

Ok, I RTFM and could answer the question myself. According to k204.pdf (attached to the newly created EWSD-LTGF - Retronetworking - Open Source Mobile Communications), LTGF exist in two functions: B or C function.

  • in B-function, it can support DLU (local or remote)
    • E1 / S2M towards PBX
    • V5.2 AN
  • in C-function, it can support only digital interconnect (PDC)

Sadly, the above-mentioned PDF only contains a picture of the LTGF in B-function, and not the C-function:

This doesn’t correspond to the LTGF at the DIVF I encountered, primarily they contain no GS (PSC, MCAA, MCAB, GSC). So maybe that’s means it’s a C-function?

Indeed, it seems like those are LTGF in C-Function:

This means those LTGF cannot directly attach anything except PCM30 with CAS or CCS or Announcements. They are not suitable to directly attach DLU or ISDN PRI, which would require B-Function:

Hello Harald,

in my opinion and the EWSD-Konstruction handbook say the same:
You can use the LTGF Frame as LTGC for Trunks or as LTGB for DLU.
For the LTGB Funktion you need same additional cards. If the Frame contains all cards for the LTGB function you can use it also for the LTGC function.
If the Frame only contains the cards for LTGC funktion you can only use it as LTGC.

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