[Proj] Projection doesn't use +towgs84 parameters

[Dražen Odobašić]

Hi,

i'm having an issue with transformation between two coordinate systems 
using cs2cs. I've noticed this while trying to use gdalwrap, but using 
cs2cs has same results.

This is what im trying to execute:

cs2cs +proj=tmerc +lat_0=0 +lon_0=15 +k=0.9999 +x_0=5500000 +y_0=0 
+ellps=bessel 
+towgs84=514.0188,155.448,507.0461,5.6136,3.676,-11.4667,0.9999979090043 
+units=m +no_defs +to +proj=tmerc +lat_0=0 +lon_0=16.5 +k_0=0.9999 
+x_0=500000 +ellps=WGS84 +units=m +no_defs -v
#
# ---- From Coordinate System ----
#
#Transverse Mercator
#
#       Cyl, Sph&Ell
#
# +proj=tmerc +lat_0=0 +lon_0=15 +k=0.9999 +x_0=5500000 +y_0=0 +ellps=bessel
#
# +towgs84=514.0188,155.448,507.0461,5.6136,3.676,-11.4667,0.9999979090043
#
# +units=m +no_defs
#
# ---- To Coordinate System ----
#
#Transverse Mercator
#
#       Cyl, Sph&Ell
#
# +proj=tmerc +lat_0=0 +lon_0=16.5 +k_0=0.9999 +x_0=500000 +ellps=WGS84
#
# +units=m +no_defs
#
5549500.250000 5060999.750000
#
432679.49       5061680.25 0.00


When i try to set any other +towgs84 params, the result is the same:


cs2cs +proj=tmerc +lat_0=0 +lon_0=15 +k=0.9999 +x_0=5500000 +y_0=0 
+ellps=bessel +towgs84=1,1,1,1,1,1,1 +units=m +no_defs +to +proj=tmerc 
+lat_0=0 +lon_0=16.5 +k_0=0.9999 +x_0=500000 +ellps=WGS84 +units=m 
+no_defs -v# ---- From Coordinate System ----
#
#Transverse Mercator
#
#       Cyl, Sph&Ell
#
# +proj=tmerc +lat_0=0 +lon_0=15 +k=0.9999 +x_0=5500000 +y_0=0 +ellps=bessel
#
# +towgs84=1,1,1,1,1,1,1
#
# +units=m +no_defs
#
# ---- To Coordinate System ----
#
#Transverse Mercator
#
#       Cyl, Sph&Ell
#
# +proj=tmerc +lat_0=0 +lon_0=16.5 +k_0=0.9999 +x_0=500000 +ellps=WGS84
#
# +units=m +no_defs
#
5549500.250000 5060999.750000
#
432679.49       5061680.25 0.00


I'm using proj.4 4.7.1, and i've tried using 4.6.1, with the same 
results. Am i doing something wrong?