C.2.10 Select compression method +VSM

27.0073GPPAT command set for User Equipment (UE)Release 18TS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

This selects the voice compression method <n1>, the voice sampling rate <n2>, the silence compression sensitivity <n3>, and a parameter related to silence expansion <n4>. There are several choices of compression method. IS‑101 does not specify methods, but here is a list of some usual compression methods:

Name Communications system

GSM/full‑rate GSM

GSM/half‑rate GSM

ADPCM/G.721 DECT, CT2

ADPCM/G.723 DECT, CT2

ADPCM/G.726 DECT, CT2

ADPCM/G.727 DECT, CT2

SIGNED PCM POTS

Table C.17: +VSM parameter command syntax

Command	Return
+VSM=<n1>,<n2>,<n3>,<n4>
+VSM?	<n1>,<n2>,<n3>,<n4>
+VSM=?	complex; refer IS‑101

NOTE: A value of <n3>=0 implies no silence compression sensitivity. A value of <n4>=0 implies no silence expansion.