TORONTO -- Telus Corp. has joined Rogers Communications Inc. in saying it can't meet a Dec. 1 deadline for completing changes to the way customers are billed for extra data usage and international roaming charges.

Vancouver-based Telus (T.TO) is asking the CRTC for permission to extend the deadline for updating its billing system to March 31, 2018 -- although it anticipates some changes will be complete before that time.

Canada's wireless carriers were told last June that they had until Dec. 1 to comply with a number of regulations including how they set caps on wireless data usage and who is authorized to accept extra charges for accounts with more than one device user.

In a letter to the CRTC, Telus says it's "impossible" for the company to implement the changes to its bill management system on time despite its "best efforts."

The CRTC gave Canada's wireless carriers until 8 p.m. ET on Friday to respond to delays requested by Rogers (RCIb.TO).

Rogers requested a delayed deadline of May 31, 2018, to have its billing system in compliance with the wireless code.

A redacted version of the Telus request, dated Nov. 16, was posted on the CRTC's website late Friday.