Programming :: Sed To Remove Non-numerics From Phone Numbers?

Can sed remove non-numerics (apart from an optional leading +) from phone numbers when prefixed with text that must be retained? The need is to make phone numbers exported from an Orage address book to a .ldif file suitable for gnokii to send to a mobile phone. Here are sample lines:

Code:
facsimiletelephonenumber: +91 (123) 1234567
telephoneNumber: +44 (123) 1234567

They have to end up as:

Code:
facsimiletelephonenumber: +911231234567
telephoneNumber: +441231234567

I could do it in awk but am curious to learn if sed can do it.