I am able to make outbound calls, but unable to receive inbound calls
This is most likely due to intermediate device like Router/Firewall blocking UDP ports for SIP. Make sure you're router or firewall has ports opened for SIP, RTP, etc like 5060, 5004. One way to check is by configuring a STUN Server (you can find free public STUN Server settings online) and then noticing the NAT type under STATUS page. If it says 'NAT type is full cone' you should be fine, but if it says symmetrical or port-restricted, you will need to make adjustments on the intermediate device.
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