Questions on mixing POTS and SIP lines

We have SIP trunks and 4 POTS lines.
Because of internet instability we want to route outgoing calls over the POTS lines, then spillover to SIP trunk if additional calls go out.

Incoming calls are all DIDs, so we will leave on SIP trunk-no one line gets so much traffic (other than COO) and majority of calls are outgoing. With the exception of the COO: we would like to have calls come in over an analog line (if it’s available, may need to dedicate a channel just for her primary use?), but spillover to one of the others - maybe just to her SIP line, a call hunt which probably would need to be set up on the SIP providers side?

The other big question is how can I (if I can) set up the outgoing CID to be set to the users DID, overriding the POTS number?

Most of that yu will have to talk to your POTS provider, ask her :-

  1. Are they in hunt
  2. If so, what is the “Lead Number”
  3. if not, how does her “call forward busy” work
  4. do the “back lines” also have associated numbers
  5. How much per channel does that “call forwarding” cost per channel
  6. When you are Sh*t outta" of inbound channels, will the CFB to an external number (your SIP DID)

You need to watch for “glare”, which is when an inbound POTS call collides with an outbound one, you should ensure your dahdi groups are in reverse to how you arranged your inbound calls (use G0 OR g0 as appropriate), spillover is done internally in your outbound routes, please read the WIKI :wink:

The other “big answer” is NO , not on an analog POTS line, the CallerID is always “Channel Associative”


You can set up each users CID to override the default CID by going to applications-extensions then click on the users you’d like to adjust. Make sure the user’s CID is forced regardless of other rules.

Not possible on POTS.
Possible on SIP if your provider allows it.

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