Trunk selection and device selection are two separate processes. Give it a shot and see if the sip server will prefer the new trunk over the old one on inbound.
Device Selection Procedure
SIP Server makes its selection from the pool of compatible devices in the
following order of descending priority:
1. "Prefix match"
2. "Current availability"
3. "Partition-id parameter"
4. "Geo-location attribute"
5. "Cpd-capability parameter"
6. "Priority attribute"
7. "Percentage of used capacity"
8. "Round-robin"
Prefix match SIP Server first narrows the pool of devices by matching the prefix option as
defined on the DNs. SIP Server chooses the longest match possible. For
example, if SIP Server finds some devices with a prefix of 90 and other devices
with a prefix of 900, SIP Server narrows the pool to those devices that have the
longer prefix of 900.
Current availability SIP Server further narrows the pool to those devices that are currently in
service. For example, if the maximum capacity for the device has been
reached, or if the device has been marked as temporarily unavailable, SIP
Server does not consider the device.
Partition-id
parameter
SIP Server uses the partition-id parameter to select a service based on the
partition to which the call belongs.
Geo-location
attribute
Services that have the same geo-location as the target are preferred over all
others. If no matching geo-location is found, or if no geo-location is configured
-Ivan