A method for routing an Internet Protocol, IP, - based call through a first IP-based network to a second IP-based network, the method comprising: receiving at a core routing engine a Session Initiation Protocol SIP-based call request in the first network; extracting at the core routing engine a called telephone number from the call request; identifying from among a plurality of route labels a route label associated with the called telephone number, each said route label having an associated set of trunk group identifiers; identifying, from among the set of trunk group identifiers associated with the identified route label, one or more IP trunk groups (512, 514, 516) that can be used to route the call request out of the first network, wherein each of the one or more IP trunk groups (512, 514, 516) represents a logical grouping of one or more IP interconnections (502a - 502n) between the first IP -based network and the second IP-based network; selecting one of the identified one or more IP trunk groups (512, 514, 516); and routing the received call request to an IP address (508, 510a - 510n) associated with the selected IP trunk group, wherein the selecting one of the identified one or more IP trunk groups (512, 514, 516) comprises selecting the IP trunk group based on an IP trunk group, IPTG, traffic distribution policy (708a - 708n) specifying how to distribute calls among IPTGs within a set of IPTGs, wherein the IP trunk group, IPTG, traffic distribution policy (708a - 708n) is associated with the identified route label. - based call through a first IP-based network to a second IP-based network, the method comprising: receiving at a core routing engine a Session Initiation Protocol SIP-based call request in the first network; extracting at the core routing engine a called telephone number from the call request; identifying from among a plurality of route labels a route label associated with the called telephone number, each said route label having an associated set of trunk group identifiers; identifying, from among the set of trunk group identifiers associated with the identified route label, one or more IP trunk groups (512, 514, 516) that can be used to route the call request out of the first network, wherein each of the one or more IP trunk groups (512, 514, 516) represents a logical grouping of one or more IP interconnections (502a - 502n) between the first IP -based network and the second IP-based network; selecting one of the identified one or more IP trunk groups (512, 514, 516); and routing the received call request to an IP address (508, 510a - 510n) associated with the selected IP trunk group, wherein the selecting one of the identified one or more IP trunk groups (512, 514, 516) comprises selecting the IP trunk group based on an IP trunk group, IPTG, traffic distribution policy (708a - 708n) specifying how to distribute calls among IPTGs within a set of IPTGs, wherein the IP trunk group, IPTG, traffic distribution policy (708a - 708n) is associated with the identified route label. receiving at a core routing engine a Session Initiation Protocol SIP-based call request in the first network; extracting at the core routing engine a called telephone number from the call request; identifying from among a plurality of route labels a route label associated with the called telephone number, each said route label having an associated set of trunk group identifiers; identifying, from among the set of trunk group identifiers associated with the identified route label, one or more IP trunk groups (512, 514, 516) that can be used to route the call request out of the first network, wherein each of the one or more IP trunk groups (512, 514, 516) represents a logical grouping of one or more IP interconnections (502a - 502n) between the first IP -based network and the second IP-based network; selecting one of the identified one or more IP trunk groups (512, 514, 516); and routing the received call request to an IP address (508, 510a - 510n) associated with the selected IP trunk group, wherein the selecting one of the identified one or more IP trunk groups (512, 514, 516) comprises selecting the IP trunk group based on an IP trunk group, IPTG, traffic distribution policy (708a - 708n) specifying how to distribute calls among IPTGs within a set of IPTGs, wherein the IP trunk group, IPTG, traffic distribution policy (708a - 708n) is associated with the identified route label.