I just got this information from KSE regarding using its Truefax 2 with the Compaq Wireless GSM/GPRS pack. Truefax doesn't supports Fax Class 2 (but Fax Class 1 only) which is supported by the Wireless Pack only! So if you want to use your Wireless Pack for fax also, you can not use it with Truefax today! Be aware of it!
KSE is working on a solution for this but can not give an upgrade date today. If anything will be available I will give you an update here!
Cheers ~ Arne