derketo-rick - welcome to the forum.
This may take a few postings. I'm also in the UK, though I use
sipgate.co.uk as my main sip service.
QuoteUK, using BT landline and DECT hansets, PSTN connection absolutely fine.
I bet we can reduce outgoing and incoming delays here (digitmap tuning), but that can wait for a while.
QuoteUsing Voipfone, SIP registers fine and I can call out on SIP fine with **1 prefix, but with 40 second delay before other end starts ringing (with silence in handset earpiece whilst waiting).
Ten seconds of the delay is probably digitmaps again. If not already set, then try setting Outbound Proxy:
Service Providers > ITSP Profile A > SIP > OutboundProxy:
sip.voipfone.netService Providers > ITSP Profile A > SIP > OutboundProxyPort: 5060
QuoteMain problem is for inbound SIP calls - handset rings but answering on handset does not answer the SIP call - eventually times out to voice mail.
Outboundproxy may have helped with this. More likely is that your router is blocking the ports used for RTP, which is the speech part of the call. Most routers will allow you to put one or more devices in "DMZ". This effectively forwards all ports to the device. If you need to find the local ip address of your OBi, then dial ***1 from the phone connected to the OBi. If this fixes things, then take the OBi out of DMZ and set up port forwarding in your router:
TCP Ports: 6800, 5222, 5223
UDP Ports: 5060, 5061, 10000 to 11000, 16600 to 16998, 19305
Make changes to your OBi settings via the Obi Expert Configuration pages. From your OBi Dashboard, click on your OBi number and follow the prompts to get there. To change a value uncheck both boxes to the right of the value and leave them unchecked. After changing the values on one page, press submit at the bottom of the page and wait a few minutes for the Obi to reboot. Then move on to the next page if required.
Hopefully, the above will get your OBi working roughly, then we can do the fine tuning!