For SIP/Voice interconnect it's mandatory to always use a tech prefix, this is how NeuTrafiX differentiates between sellers to route through on the platform. For voice, you can use the routing groups feature to use up to 3 sellers under one Routing Group special prefix. 


Note that the restriction of 3 is applicable to Failover/Order routing group only. Not to LCR or % distribution (load balancing).
 
Check this KB article for more details on this matter: https://neutrafix.freshdesk.com/support/solutions/articles/67000251429-routing-groups