Vail SIP TIM 1.0.4 supports hairpin transfers. From a MSS point of view, if a transfer is requested (as opposed to Conference), the speech resources are released after the call is connected. On the VoIP Vail SIP TIM side, we allow for double the number of ports of a given SKU. For example, on a system running a 16 port Vail SIP TIM, we provide a total of 32 ports, 16 for inbound legs and 16 for transfer legs.

Please note: Vail SIP TIM 1.1 supports SIP REFER for non-hairpin call transfers.