@rhiados (and for all)
To avoid overheating of pins and electric circuit it's better to solder a male strip into the modem (JTAG connectori) and use fenal pin (solder to wire) to connect the wire.
In this way you can obrtain the better results.
1) The modem has a permanent connection without connecting removing solder wires.
2) You can use the JTAG on different modem (is not soldered directly)