That’s a network connection consideration. In CM you have no control over this. You’d have to work with the network team and provider if it’s connected via WAN.
Not sure I get what you mean. CM will route based on the static configuration you have put in, it won't by magic use any SIP trunks you have. Even if you where using GDPR to advertise and distribute numbers between your CMs it would use static information to route based on learned route strings and manually created SIP route patterns in each CM that in it self just points to a route list.
If you mean that you'd have to wait for inter-digit timeout before the call egress out from one CM to the other that would mean you have an overlap in your dial plan and that's simply bad design.
Would you be able to provide some additional information about your setup so that we better understand your current situation and your needs? For example outline what the called and calling numbers are and what configuration you have put in to route the call from one CM to the other. For this include any translation and route pattern(s), route list, route group and trunks you have in the path.
Then I would recommend you to look at your design and amend it to not have that overlap.
One option that comes to mind would be to use GDPR and announce the individual numbers between the two CMs and set these to be urgent priority in the GDPR configuration partition page. That way each CM will directly route the call as soon as it has a complete match for the called number, no matter if it’s a number in the local or in the remote CM.
