White noise during silences

Hi

When asterisk recieves an incoming call and I want Asterisk to wait, I Playback or Background silence and all is well. If asterisk is mearly busy (I’m guessing no RTP is being sent) the caller can hear a fairly off-putting hiss.

There are times when Asterisk is busy doing something with a call and therefore cannot Playback or Background silence is there anyway I can make these moments silent?

One example is this:

Call comes in.
Asterisk asks caller to hold
Asterisk starts music on hold
After 50 seconds, asterisk Curls a pager throug HTTPS (caller hears the hiss)
Asterisk apologises for the delay and returns to music on hold.

Thanks.

Chrisp