Hello, devs, i have this situation.<div>if FS sends an INVITE to a Nortel switch and the Nortel answer is SIP 503, FS does not send the ACK to the Nortel, any guidance please.</div><div><br></div><div>Here is a trace of the Nortel answer.</div>
<div><br></div><div><br></div><div><div style="font-family:Georgia;font-size:12px;margin:0px"><font face="Monaco">SIP/2.0 503 Service Unavailable.</font></div><div style="font-family:Georgia;font-size:12px;margin:0px"><font face="Monaco">Via: SIP/2.0/UDP 67.220.147.141;received=67.220.147.141;branch=z9hG4bK5Q6g5UjNZeQZr;rport=5060.</font></div>
<div style="font-family:Georgia;font-size:12px;margin:0px"><font face="Monaco">From: &quot;9143345048&quot; &lt;<a href="sip:+9143345048@67.220.147.141">sip:+9143345048@67.220.147.141</a>&gt;;tag=5maaU2Sa3gNHH.</font></div>
<div style="font-family:Georgia;font-size:12px;margin:0px"><font face="Monaco">To: &lt;<a href="sip:+59386510685@190.166.232.141;user=phone">sip:+59386510685@190.166.232.141;user=phone</a>&gt;;tag=f1b31366541302012101718172.</font></div>
<div style="font-family:Georgia;font-size:12px;margin:0px"><font face="Monaco">Call-ID: 37e5bc92-934b-1230-4986-782bcb61be68.</font></div><div style="font-family:Georgia;font-size:12px;margin:0px"><font face="Monaco">CSeq: 34920047 INVITE.</font></div>
<div style="font-family:Georgia;font-size:12px;margin:0px"><font face="Monaco">Server: CS2000_NGSS/9.0.</font></div><div style="font-family:Georgia;font-size:12px;margin:0px"><font face="Monaco">k: 100rel.</font></div><div style="font-family:Georgia;font-size:12px;margin:0px">
<font face="Monaco">Allow: ACK,BYE,CANCEL,INVITE,OPTIONS,INFO,SUBSCRIBE,REFER,NOTIFY,PRACK,UPDATE.</font></div><div style="font-family:Georgia;font-size:12px;margin:0px"><font face="Monaco">Content-Disposition: signal;handling=optional.</font></div>
<div style="font-family:Georgia;font-size:12px;margin:0px"><font color="#e32400" face="Monaco">c: application/ISUP;version=.</font></div><div style="font-family:Georgia;font-size:12px;margin:0px"><font color="#e32400" face="Monaco">Content-Length: 6.</font></div>
</div><div style="font-size:12px;margin:0px"><font color="#e32400" face="Monaco">......</font></div><div style="font-size:12px;margin:0px"><font color="#e32400" face="Monaco"><br></font></div><div style="font-size:12px;margin:0px">
<font face="Monaco">Thanks in advance for your help.</font></div><div style="font-size:12px;margin:0px"><font face="Monaco"><br></font></div><div style="font-size:12px;margin:0px"><font face="Monaco"><br></font></div><div style="font-size:12px;margin:0px">
<font face="Monaco">Luis Jiménez</font></div><div style="font-size:12px;margin:0px"><font color="#e32400" face="Monaco"><br></font></div><div style="font-size:12px;margin:0px"><font color="#e32400" face="Monaco"><br></font></div>
<div style="font-size:12px;margin:0px"><font color="#e32400" face="Monaco"><br></font></div>