caller hears no ringtone

[wesdavies70507]

I have a Sp112- Recently installed with ddi number via voipdiscount Everything is working fine or at least seems to be- APART from

When there is an incoming call- The phone rings no problem- But the caller receives no ringtone.

When you dial the number there is simply silence until the handset is picked up.

I cannot figure out why caller receives no ringtone- Any help appreciated

[Dan Lukes]

Content of valuable advice depends no details  you decided to keep secret.

Incoming call is initiated by SIP INVITE message and responded by a 18x response from SPA112. We need to know at least content of such 18x  response to advise something valuable.