Incoming call ----> call to SIP/landline/mobile using provider's trunk

Hello everybody

Desperately looking for some answers…

I need to redirect incoming call and to send SIP URI or phone number directly to SIP-provider’s trunk.

I’ve choosen this chain:

TRUNK1 (trunk from which incoming call arrives. State OK)
TRUNK2 (SIP services provider’s trunk. State OK)

ROUTE1 (inbound route which Set Destination parameter points to CustomTrunk) ->
CustomTrunk (this is a CustomTrunk with Custom Dial String parameters:

SIP/TRUNK2/[email protected]
(NOT WORKING)
or
SIP/[email protected]
(WORKING. Very strange, because no trunk is binded in this case)
or
SIP/TRUNK2/landline_tel_number
(NOT WORKING)

Would you tell me what am I doing wrong, please…