Endpoint Tranfer to Parking Lot Problem

I’m trying to make parking work using a SIP phone’s transfer button, not Asterisk’s blindxfer keys. The problem I am facing is that music on hold stops for the parked leg once the transfer is bridged. The call is parked correctly but no music is heard.

This problem does not exist when using Asterisk’s blindxfer keys but I want to avoid this.

ValetParking does not display this behaviour and works correctly. But I’d prefer to use Asterisk’s parking feature over a third-party addon that I believe is no longer maintained.

[EDIT]
ValetParking does indeed produce the same behavior some minutes after an Asterisk restart. I imagine that regular parking would behave the same way: MOH for parked call works for first few parkings then stops for subsequent parkings.

This appears to be known issue judging from the bug reports. Hopefully somebody will fix it before 1.4
[/EDIT]

Any ideas?

How does the caller connect? Is the caller, that is being parked, connecting through a SIP, IAX, or Zap channel?

Connected via SIP. Or ZAP, it does not matter. Haven’t tried IAX.

The problem seems to be that Asterisk stops MOH because it senses a channel hangup. Meaning, A calls B. B does endpoint attended transfer (not Asterisk transfer) into parking lot. The attended transfer is needed in order to hear what spot we’re in. B bridges A into parking. Now we actually have both A & B in the parking spot (3-way calling). B hangs up, MOH stops. But A is in fact still parked.