Replace an ISDN or E1/T1 service
Map the current signaling and capacity to the digital or SIP role required by the target carrier service.
Move from ISDN and PSTN to IP voice with confidence.
Keep established calling services connected as ISDN and PSTN networks are retired. Move affected trunks and dependencies to SIP through a planned migration, validating signaling, numbering and call flows before cutover.
The external trigger
Turn network retirement into a managed migration.
When an operator retires an ISDN or PSTN service, the impact extends beyond the line itself to PBXs, numbers, trunks and analog devices that still depend on it.
The migration must identify every affected service, preserve necessary calling behavior during the transition and establish the correct digital, analog or SIP replacement path.
Keep the existing PBX during transition
Use analog, digital or SIP interworking while the core system remains in service.
Route non-ISDN work separately
Move retained analog devices and POTS services into the dedicated analog migration workflow instead of treating them as an E1 gateway task.
Sequence several locations
Plan each site around its carrier date, local equipment and approved migration window.
Migration decision path
Keep the ISDN PBX while moving its E1 or T1 handoff to SIP.
DGW-L304 provides the four-span digital boundary shown in the migration path; DGW-L301 and DGW-L302 remain lower-span choices after the trunk inventory is verified.
- 01Retained ISDN PBX
Existing numbering, phones and business behavior
- 02E1 / T1 handoff
Verified signaling and span count
- 03DGW-L304
Four-span digital-to-SIP migration boundary
- 04SIP service or IP-PBX
Target calling environment
- 05IP phones and remote users
New endpoints added after interworking is accepted
Record every affected handoff
Separate carrier services from phones, PBXs and cabling that may remain.
Choose by span count
Use DGW-L301, DGW-L302 or DGW-L304 only after the E1 or T1 requirement is confirmed.
Prove the replacement before cutover
Validate signaling, routing and rollback for each migrated group.
Select the DGW model from the verified digital span count.
DGW-L304 is the four-span reference shown here; DGW-L301 and DGW-L302 cover one- and two-span projects using the same interface-led migration method.
Primary product
DGW-L304
Four-span E1, T1 or J1 migration gateway shown in the approved architecture
View product
Optional when needed
DGW-L302
Two-span digital capacity option
Use when: Use only when two digital spans are required.
View product
Optional when needed
DGW-L301
One-span digital capacity option
Use when: Use only when one digital span is required.
View productVerified evidence for migration.
Country-specific retirement dates must be confirmed with the relevant operator or regulator.
Authoritative dates only
The project confirms the current operator or regulator timeline before publishing urgency claims.
Proof chips
- TRIGGER
Documented trunk options
OpenVox digital products support selectable E1/T1/J1 and signaling roles on documented models.
Proof chips
- DIGITAL
Device and line access
FXS and FXO products support different sides of the analog migration.
Proof chips
- ANALOG
Target network interworking
UCP and gateways support standard SIP connections to documented IP voice environments.
Proof chips
- SIP
Build a controlled switch-off schedule.
Share the country, operator, retained ISDN PBX, signaling, span count, numbers and target SIP service. OpenVox can help select the DGW capacity and validation plan.