msc {
  hscale="2";

  ms[label="MS/BTS"],bsc[label="BSC"],smlc[label="SMLC"],__msc[label="MSC"];

  ||| [label="Location Services (LCS): Perform Location Request using TA"];

  |||;
  --- [label="MS in DEDICATED MODE (currently active)"];

  ms =>> bsc [label="earlier Measurement Report provides Timing Advance"];

  bsc <<= __msc [label="PERFORM LOCATION REQUEST\n3GPP TS 48.008 3.2.1.71"];

  bsc =>> smlc [label="BSSMAP-LE PERFORM LOCATION REQUEST\n3GPP TS 49.031 9.1\nwith BSSLAP APDU = TA Layer3\n3GPP TS 48.071 4.2.8"];

  smlc rbox smlc [label="SMLC uses TA included in TA Layer3"];

  bsc <<= smlc [label="BSSMAP-LE PERFORM LOCATION RESPONSE\n3GPP TS 49.031 9.2"];

  bsc =>> __msc [label="PERFORM LOCATION RESPONSE\n3GPP TS 48.008 3.2.1.72"];

  ...;
  ...;
  --- [label="MS in IDLE MODE (not connected)"];

  bsc <<= __msc [label="PERFORM LOCATION REQUEST\n3GPP TS 48.008 3.2.1.71"];

  bsc =>> smlc [label="BSSMAP-LE PERFORM LOCATION REQUEST\n3GPP TS 49.031 9.1"];

  smlc rbox smlc [label="SMLC needs TA information,\nasks BSC via BSSLAP"];

  bsc <<= smlc [label="BSSMAP-LE CONNECTION ORIENTED INFORMATION\n3GPP TS 49.031 9.12\nwith BSSLAP APDU = TA Request\n3GPP TS 48.071 4.2.1"];


  ms <<= bsc [label="RR Paging Request\n3GPP TS 48.018 9.1.22-24"];

  ms =>> bsc [label="RSL CHANNEL REQUIRED\n3GPP TS 48.058 8.5.3\nincludes Access Delay (9.3.17) == Timing Advance"];

  ms =>> bsc [label="RR Paging Response\n3GPP TS 48.018 9.1.25"];

  ms <<= bsc [label="RF CHANNEL RELEASE\n3GPP TS 48.058 8.4.14"];

  bsc =>> smlc [label="BSSMAP-LE CONNECTION ORIENTED INFORMATION\n3GPP TS 49.031 9.12\nwith BSSLAP APDU = TA Response\n3GPP TS 48.071 4.2.2"];

  bsc <<= smlc [label="BSSMAP-LE PERFORM LOCATION RESPONSE\n3GPP TS 49.031 9.2"];

  bsc =>> __msc [label="PERFORM LOCATION RESPONSE\n3GPP TS 48.008 3.2.1.72"];
}