Is their a way to direct VoIP traffic through WAN1 and data traffic through WAN2?
Yes. Default rule sending all traffic via WAN2, the above that a set of rules, either by source IP (reserved or static IPs assigned to VoIP handsets), destination IP (of your hosted SIP server), or ports (SIP 5060, and whatever RTP ports you use).
Generally we stick VoIP handsets on a dedicated VLAN with its own subnet so that we can use one rule to manage all VoIP traffic (eg source - network 192.168.51.0/24)
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