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 their dependencies to SIP through a planned migration, validating signaling, numbering, and call flows before cutover.

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Move from ISDN and PSTN to IP voice with confidence.

The external trigger

Turn network retirement into a managed migration.

When a carrier retires an ISDN or PSTN service, the impact goes beyond the line itself to affect the PBXs, numbers, trunks, and analog devices that still depend on it.

The migration must identify every affected service, preserve the required calling behavior during the transition, and establish the correct digital, analog, or SIP replacement path.

DIGITAL TRUNK

Replace an ISDN or E1/T1 service

Map current signaling and capacity to the digital or SIP role required by the target carrier service.

LEGACY PBX

Keep the existing PBX during transition

Use analog, digital, or SIP interoperability while the central system remains in service.

ANALOG DEPENDENCIES

Route non-ISDN work separately

Move retained analog devices and POTS services into the dedicated analog migration flow instead of treating them as an E1 gateway task.

MULTISITE

Sequence multiple sites

Plan each site around its carrier date, local equipment, and approved migration window.

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 trunk inventory verification.

Select the DGW model based on the verified number of digital spans.

DGW-L304 is the four-span reference shown here; DGW-L301 and DGW-L302 cover one-span and two-span projects using the same interface-based migration method.

Verified migration evidence.

Country-specific retirement dates must be confirmed with the relevant carrier or regulator.

Authorized dates only

The project confirms the carrier's or regulator's current schedule before publishing urgency claims.

Documented trunk options

OpenVox digital products support E1/T1/J1 roles and selectable signaling on documented models.

Device and line access

FXS and FXO products support the different sides of analog migration.

Target network interoperability

UCP and gateways support standard SIP connections to documented IP voice environments.

Build a controlled cutover schedule.

Share the country, carrier, retained ISDN PBX, signaling, span count, numbers, and target SIP service. OpenVox can help select DGW capacity and the validation plan.

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