Pull back a call from hold

[digitel]

I'll explain better the sequence:

A call rings my T28P
I answer the call
I press the BLF key configured as " BLF - Extno. - Line1 - ** " (the ** is the direct call pickup feature in asterisk)
The called extensions rings (the call hears MoH)

Case1

The called extension doesn't answer:
Pushing BLF has no effect
Pushing Line1 button stops the extension to be called and HOLD is displayed (incoming call is still hearing MoH)
Pushing a second time Line1 button (or resume button) resumes the call.

Case2
The called extension answers but doesn't like to join the caller on hold:
If the called extension hangs , HOLD is displayed and a single push of Line1 or "resume" button , resumes call otherwise I have to push Line1 twice or Line1 plus "resume" like previous case.


P.S.

I had to configure BLF key with ** in extension field to pickup the call when THAT extension rings (and BLF blinks red) by pushing BLF key
In fact, pushing BLF when blinking it dials **EXTno. (the code for direct dial pickup in asterisk)
In alternative, I can leave the "Extension" field empty and set ** in
Account --> Advanced --> Directed Call Pickup Code
Setting the extension number in "Value" field as well as in the "Extension" field causes double extno. to be dialed when picking up a call (resulting in an dial error to asterisk)
Some comment appreciated also on this kind of settings

Thanks