Sip registration Failed - 503 on SPA504G

[bytesolutions]

Good morning everyone.
I have an installation with 3CX SMB, a local SBC and three Cisco SPA 504G phones manually provisioned to 3CX via this SBC.
Everything works correctly, but sometimes (I think when there are internet connectivity problems or other) the phones lose registration and show "Failed - 503".
I just need to restart the phones to make them register correctly, but I would like to understand why they do not attempt a new SIP registration autonomously. I think it is a timeout problem but I am not sure. Can anyone advise me which parameters to change?
I report below the complete SIP configuration of the Cisco SPA504G

thanks in advance to everyone

 

[Fabian Jsn]

Hi, hope it help

Proxy and Registration
Proxy : 192.168.1.16
Register : yes

Subscriber Information
Display Name : 1000 UserA
Password : password
Auth ID : Auth ID
User ID : 1000

Make sure, SBC can ping to IP Phone

 

[Fabian Jsn]

for your reference https://www.3cx.com/sip-phones/cisco-spa/

 

[fortech]

Hi, this really sounds like a 'client config default behaviour kind of stinks' sort of issue? And maybe because the phones are manually provisioned, they are lacking desired settings which might otherwise be tweaked to make things work more smoothly (?)
I'm assuming you have dug through cisco docs to try to find a way to adjust behaviour for "reconnect please automatic" or something like that (?)

If my googles are correct, these phones are maybe kind of old. So one possible recommended solution might be
(a) buy 3x phones which are modern and well supported. I'm sure you can get something for ~$100 per unit or less even if you dig on Ebay/auction/clearance/openbox etc.
(b) Then, use the cisco units as paperweights, my oh my hey are very pretty.
(c) life goes on.

But possibly that is not the most helpful answer. But I do know for sure from my own adventures in manual unsupported 3cx phone and handset config - that finding good settings via web admin on the handset - can be important (ie, critical).

Alas I have no experience with this cisco unit so I can't speak to it precisely. I did bang my head on a different old cisco handset a few years ago, and after wasting >1 hour or more trying to read a hellscape of overly-complex-cisco-documentation, eventually I gave up and realized life was too short to try to recycle an old phone in this situation.

Otherwise, the web-app and the smartphone apps do work great and they price point for them is just lovely ($0.00 per unit) :

Tim