Local SIP and RTP ports for 2 phones

[SantSoln]

We have few customers with just 2 to 3 phones using Grandstream GXP2130/2135 phones. Both phones are in a Ring Group for incoming calls. We are not able to put an SBC due to cost reasons so using STUN. Everything was working OK until now where the 2nd phone doesn't ring. The Local SIP Port of both phones were assigned as 5065 and the Local RTP Audio Ports Start is 14000 and ends with 14019. Can I reassign the 2nd port to a different SIP Port and/or RTP Ports to something different? Surely, others are running into similar situations... System is Hosted and Running System 18.0

Appreciate any recommendations...

 

[Evolute IT]

Everything was working OK until now where the 2nd phone doesn't ring.

That's why STUN is not a good option.

Why not use the app/Webclient? Cheaper than using an SBC.