(a) No telephone corporation shall suspend service for nonpayment of bills rendered for service, or for failure to post a required deposit, until:

1. (1) at least five days after written notice has been served personally upon the telephone subscriber;
2. (2) at least eight days after mailing written notice in postpaid wrapper to the telephone subscriber, addressed to such subscriber at premises where service is rendered; or
3. (3) at least five days after the telephone subscriber has either signed for or refused a registered letter containing written notice addressed to such subscriber at premises where service is rendered.

(b) No telephone corporation shall terminate service for nonpayment of bills rendered for service, or for failure to post a required deposit, until:

1. (1) at least 10 days after written notice has been served personally upon the telephone subscriber;
2. (2) at least 13 days after mailing written notice in postpaid wrapper to the telephone subscriber, addressed to such subscriber at premises where service is rendered; or
3. (3) at least 10 days after the telephone subscriber has either signed for or refused a registered letter containing written notice, addressed to such subscriber at premises where service is rendered.